This paper introduces the principle of PPS-based adaptive cluster sampling method and its modified HH estimator and HT estimator calculation method. It compares PPS-based adaptive cluster sampling method with SRS samp...This paper introduces the principle of PPS-based adaptive cluster sampling method and its modified HH estimator and HT estimator calculation method. It compares PPS-based adaptive cluster sampling method with SRS sampling and SRS-based adaptive group. The difference between the group sampling and the advantages and scope of the PPS adaptive cluster sampling method are analyzed. According to the case analysis, the relevant conclusions are drawn: 1) The adaptive cluster sampling method is more accurate than the SRS sampling;2) SRS adaptive The HT estimator of the cluster sampling is more stable than the HH estimator;3) The two estimators of the PPS adaptive cluster sampling method have little difference in the estimation of the population mean, but the HT estimator variance is smaller and more suitable;4) PPS The HH estimator of adaptive cluster sampling is the same as the HH estimator of SRS adaptive cluster sampling, but the variance is larger and unstable.展开更多
If the population is rare and clustered,then simple random sampling gives a poor estimate of the population total.For such type of populations,adaptive cluster sampling is useful.But it loses control on the final samp...If the population is rare and clustered,then simple random sampling gives a poor estimate of the population total.For such type of populations,adaptive cluster sampling is useful.But it loses control on the final sample size.Hence,the cost of sampling increases substantially.To overcome this problem,the surveyors often use auxiliary information which is easy to obtain and inexpensive.An attempt is made through the auxiliary information to control the final sample size.In this article,we have proposed two-stage negative adaptive cluster sampling design.It is a new design,which is a combination of two-stage sampling and negative adaptive cluster sampling designs.In this design,we consider an auxiliary variablewhich is highly negatively correlatedwith the variable of interest and auxiliary information is completely known.In the first stage of this design,an initial random sample is drawn by using the auxiliary information.Further,using Thompson’s(JAmStat Assoc 85:1050-1059,1990)adaptive procedure networks in the population are discovered.These networks serve as the primary-stage units(PSUs).In the second stage,random samples of unequal sizes are drawn from the PSUs to get the secondary-stage units(SSUs).The values of the auxiliary variable and the variable of interest are recorded for these SSUs.Regression estimator is proposed to estimate the population total of the variable of interest.A new estimator,Composite Horwitz-Thompson(CHT)-type estimator,is also proposed.It is based on only the information on the variable of interest.Variances of the above two estimators along with their unbiased estimators are derived.Using this proposed methodology,sample survey was conducted at Western Ghat of Maharashtra,India.The comparison of the performance of these estimators and methodology is presented and compared with other existing methods.The cost-benefit analysis is given.展开更多
Adaptive cluster sampling （ACS） has been widely used for data collection of environment and natural resources. However, the randomness of its final sample size often impedes the use of this method. To control the fi...Adaptive cluster sampling （ACS） has been widely used for data collection of environment and natural resources. However, the randomness of its final sample size often impedes the use of this method. To control the final sample sizes, in this study, a k-step ACS based on Horvitz-Thompson （HT） estimator was developed and an unbiased estimator was derived. The k-step ACS-HT was assessed first using a simulated example and then using a real survey for numbers of plants for three species that were characterized by clustered and patchily spatial distributions. The effectiveness of this sampling design method was assessed in comparison with ACS Hansen-Hurwitz （ACS-HH） and ACS- HT estimators, and k-step ACS-HT estimator. The effectiveness of using different k- step sizes was also compared. The results showed that k-step ACS^HT estimator was most effective and ACS-HH was the least. Moreover, stable sample mean and variance estimates could be obtained after a certain number of steps, but depending on plant species, k-step ACS without replacement was slightly more effective than that with replacement. In k-step ACS, the variance estimate of one-step ACS is much larger than other k-step ACS （k 〉 1）, but it is smaller than ACS. This implies that k-step ACS is more effective than traditional ACS, besides, the final sample size can be controlled easily in population with big clusters.展开更多
Objective:To reveal the distribution characteristics and demographic factors of traditional Chinese medicine(TCM)constitution among elderly individuals in China.Methods: Elderly individuals from seven regions in China...Objective:To reveal the distribution characteristics and demographic factors of traditional Chinese medicine(TCM)constitution among elderly individuals in China.Methods: Elderly individuals from seven regions in China were selected as samples in this study using a multistage cluster random sampling method.The basic information questionnaire and Constitution in Chinese Medicine Questionnaire(Elderly Edition)were used.Descriptive statistical analysis,chi-squared tests,and binary logistic regression analysis were used.Results: The single balanced constitution(BC)accounted for 23.9%.The results of the major TCM constitution types showed that BC(43.2%)accounted for the largest proportion and unbalanced constitutions ranged from 0.9%to 15.7%.East China region(odds ratio[OR]=2.097;95%confidence interval[CI],1.912 to 2.301),married status(OR=1.341;95%CI,1.235 to 1.457),and managers(OR=1.254;95%CI,1.044 to 1.505)were significantly associated with BC.Age>70 years was associated with qi-deficiency constitution and blood stasis constitution(BSC).Female sex was significantly associated with yang-deficiency constitution(OR=1.646;95%CI,1.52 to 1.782).Southwest region was significantly associated with phlegm-dampness constitution(OR=1.809;95%CI,1.569 to 2.086).North China region was significantly associated with inherited special constitution(OR=2.521;95%CI,1.569 to 4.05).South China region(OR=2.741;95%CI,1.997 to 1.3.763),Central China region(OR=8.889;95%CI,6.676 to 11.835),senior middle school education(OR=2.442;95%CI,1.932 to 3.088),and managers(OR=1.804;95%CI,1.21 to 2.69)were significantly associated with BSC.Conclusions: This study defined the distribution characteristics and demographic factors of TCM constitution in the elderly population.Adjusting and improving unbalanced constitutions,which are correlated with diseases,can help promote healthy aging through the scientific management of these demographic factors.展开更多
This work was carried out with the objective of proposing some changes in the Strand’s sampling method, in which the trees are selected in sampling units with probability proportional to its diameter for the calculat...This work was carried out with the objective of proposing some changes in the Strand’s sampling method, in which the trees are selected in sampling units with probability proportional to its diameter for the calculation of the stand density and basal area, and proportional to its height for the calculation of volume per hectare. Data used to evaluate the efficiency of the sampling of Strand in clusters were collected in stands of Pinus elliottii Engelm, located in a National Forest, Rio Grande do Sul State, Brazil. In the course of this research work it was proposed to convert the sampling unit into a cluster, structurally more efficient to obtain consistent estimates of volume and of dominant heights, using volumetric equivalence, which results in a form factor equal to one for the final calculation of volume per hectare and an indirect method to obtain the average height of Lorey. The objectives of this study were achieved, because with this methodology it is not necessary to measure heights of trees in the sampling unit, except a dominant height by cluster to evaluate sites. The development of independent estimators for basal area and volume gave rise to the proposition of an estimator for average height of Lorey, but without measuring any tree height in the sampling. The proposed methodology is an attractive solution to reduce costs in forest inventories, with the ability to have greater accuracy and scope for information at the level of compartments, without increasing the cost of sampling in comparison to that performed with units of fixed area. The use of smaller permanent sampling units with higher intensity in the compartments before the final cut will substantially increase the precision of the estimators in these management units, which will enable them to eliminate the pre-cut inventory in forest enterprises.展开更多
Aiming at the diversity of hand gesture traces by different people,the article presents novel method called cluster dynamic time warping( CDTW),which is based on the main axis classification and sample clustering of i...Aiming at the diversity of hand gesture traces by different people,the article presents novel method called cluster dynamic time warping( CDTW),which is based on the main axis classification and sample clustering of individuals. This method shows good performance on reducing the complexity of recognition and strong robustness of individuals. Data acquisition is implemented on a triaxial accelerometer with 100 Hz sampling frequency. A database of 2400 traces was created by ten subjects for the system testing and evaluation. The overall accuracy was found to be 98. 84% for user independent gesture recognition and 96. 7% for user dependent gesture recognition,higher than dynamic time warping( DTW),derivative DTW( DDTW) and piecewise DTW( PDTW) methods.Computation cost of CDTW in this project has been reduced 11 520 times compared with DTW.展开更多
The power transformer is the core equipment of a power system,and its reliable operation is crucial for maintaining the safety and stability of power grids.Dissolved gases in insulating oil are an important informatio...The power transformer is the core equipment of a power system,and its reliable operation is crucial for maintaining the safety and stability of power grids.Dissolved gases in insulating oil are an important information source for analyzing transformer operating status and fault diagnosis.At present,intelligent fault diagnosis methods for power transformers are mostly based on classification algorithms,but the diagnosis models may be relatively complicated.Some models have poor generalization ability when training samples are scarce.Clustering algorithms can better deal with this problem.Fault diagnosis of transformers based on a clustering algorithm primarily utilizes the proportional data of dissolved gases as features,which have not considered abundant gas ratio features,and those clustering methods are prone to invalid clustering.In order to solve those problems,this paper uses more features as information sources of power transformer diagnosis based on clustering method.Different clustering spaces are considered for different fault types.Clustering centers are found on samples with the same fault type,which aims to expand the data distribution difference in different fault types.This paper also uses genetic algorithm(GA)to optimize multiple data clustering spaces and improve clustering effect.Based on multiple data sets,it is verified that the proposed method can effectively avoid the occurrence of invalid clustering,and the difference among different fault types based on multiple clustering spaces method is more obvious.展开更多
Coverage of nominal 95% confidence intervals of a proportion estimated from a sample obtained under a complex survey design, or a proportion estimated from a ratio of two random variables, can depart significantly fro...Coverage of nominal 95% confidence intervals of a proportion estimated from a sample obtained under a complex survey design, or a proportion estimated from a ratio of two random variables, can depart significantly from its target. Effective calibration methods exist for intervals for a proportion derived from a single binary study variable, but not for estimates of thematic classification accuracy. To promote a calibration of confidence intervals within the context of land-cover mapping, this study first illustrates a common problem of under and over-coverage with standard confidence intervals, and then proposes a simple and fast calibration that more often than not will improve coverage. The demonstration is with simulated sampling from a classified map with four classes, and a reference class known for every unit in a population of 160,000 units arranged in a square array. The simulations include four common probability sampling designs for accuracy assessment, and three sample sizes. Statistically significant over- and under-coverage was present in estimates of user’s (UA) and producer’s accuracy (PA) as well as in estimates of class area proportion. A calibration with Bayes intervals for UA and PA was most efficient with smaller sample sizes and two cluster sampling designs.展开更多
This paper describes a structural equation modeling （SEM） analysis of factors influencing architects＇ trust in project design teams. We undertook a survey of architects, during which we distributed 193 questionnair...This paper describes a structural equation modeling （SEM） analysis of factors influencing architects＇ trust in project design teams. We undertook a survey of architects, during which we distributed 193 questionnaires in 29 A-level architectural design institutes selected radomly from the altogether 59 ones in Shenzhen, P. R. China, and received 130 valid questionnaires. We used Amos 6.0 for SEM to identify significant personal construct based factors affecting interpersonal trust. The results show that only social interaction between architects significantly affects their interpersonal trust. The explained variance of trus~ is not very high in the model. Therefore, future research should add more factors into the current model. The practical implication is that team managers should promote the social interactions between team members such that the interpersonal trust level between team members can be improved.展开更多
Fast growing poplar species enjoy a highly favored position in Iran’s forest product industries. However, information on poplar plantations, such as areas, growing stock and harvest volumes, are largely obtained by n...Fast growing poplar species enjoy a highly favored position in Iran’s forest product industries. However, information on poplar plantations, such as areas, growing stock and harvest volumes, are largely obtained by non scientific means and poorly executed methods. A few studies have been conducted to obtain data on the capacity of poplar plantations, their extent, existing growing stock, distribution and species choice in three provinces, i.e., Western Azerbaijan, Kurdistan and Hamedan, with relatively well developed management systems. We opted for a cluster method, a standard sampling method for conducting similar investigations, consisting of two phases. In the first phase we collected library information and conducted half-open interviews with villagers. In the second phase field measurements in the villages of these three provinces were carried out. Information from field measurements on growing stock, cultivated areas, dominant species were used to estimate volumes by way of volume and weight tables. Results obtained from the present study indicate that the average annual volume of timber harvested in the three provinces was 697,723 m3, with an average sampling error of 22.7 per cent. This annual volume of poplar timber harvested from the three provinces was estimated to amount to about 25 per cent of overall harvest; at that rate, the overall annual utilization potential of poplar plantations will be 10 million m3, which constitutes a reliable resource of raw timber for use in wood and paper industries.展开更多
Background: The World Health Organization (WHO) initiated the Expanded Program on Immunization (EPI) in 1974. It has been widely used in different studies. Along with this, other survey methodologies have been compare...Background: The World Health Organization (WHO) initiated the Expanded Program on Immunization (EPI) in 1974. It has been widely used in different studies. Along with this, other survey methodologies have been compared to study immunization coverage at different regions. To consider different survey methodologies, one of the most important factors is the cost incurred that survey methodology. A survey method is considered as more efficient or better than the other survey method if the cost incurred in a particular method is less than the other one. Methods: In this study, cost incurred in two stage (30 × 30) cluster sampling and systematic sampling methods have been compared using a cost function for measles vaccine coverage. Measles vaccine coverage data has been taken from the survey “Comparison of Two Survey Methodologies to Estimates Total Vaccination Coverage” sponsored by Indian Council of Medical Research (ICMR), New Delhi. Results: The results show that there are no significant differences between the point estimates of measles vaccine coverage under the considered survey methodologies. But the cost incurred in systematic sampling is more than that of two stage cluster sampling. Conclusion: It can be concluded that systematic sampling survey is costlier than that of two stage cluster sampling for this study population.展开更多
Objective To understand the occupational injury situation of front-line workers in metallurgical and shipbuilding and repairing industry,and explore the risk factors of occupational injury.Methods From September 2023 ...Objective To understand the occupational injury situation of front-line workers in metallurgical and shipbuilding and repairing industry,and explore the risk factors of occupational injury.Methods From September 2023 to March 2024,using cluster sampling method,front-line workers from 2 metallurgical enterprises in Shaoguan and Jinan City and 2 shipbuildinggand repairing enterprises in Jiangmen and Shenzhen City were selected as the investigation objects.6248 questionnaires were distributed and collected,and 6178 were effective questionnaires,with a effective recovery rate of 98.88%.The basic information,living habits,working system,protection and occupational injury of workers were investigated,and the data of occupational injury in factories was collected.The types,jobs and main causes of occupational injuries in different industries were analyzed,and the influencing factors of occupational injuries were analyzed by univariate and multi-factor logistic regression.Results The incidence of occupational injury was 3.13%(128/4086)in metallurgical industry and 4.02%(84/2092)in shipbuilding and repairing industry.The top three occupational injuries in the metallurgical industry were furnace worker(17.19%,22/128),steel rolling worker(14.84%,19/128),maintenance worker(10.16%,13/128),and the top three injury types were mechanical injury(24.22%,31/128),height fall(20.31%,26/128)and object strikes(17.97%,23/128).The top three occupational injuries in shipbuilding and repairing industry were welder(20.24%,17/84),riveter(9.52%,8/84)and crane(8.33%,7/84).The top three injury types were hit by objects(34.52%,29/84),hit by falling objects(22.62%,19/84),and lifting injury(20.24%,17/84).The injuries of workers in metallurgical industry and shipbuilding and repairing industry weremainly fractures,accounting for 32.03%(41/128)and 60.71%(51/84),respectively.The incidence of occupational injury was higher in males,with sleep disorder,high temperature exposure and chemical toxicity exposure(P<0.05).There were significant differences in age,smoking degree,working age and emotional state between workers with occupational injury and those without occupational injury(P<0.05).Multivariate analysis showed that male,age above 50 years old,moderate smoking,working years of 5-9 years,mild anxiety,poor health status and high temperature exposure were risk factors for occupational injury(0R=25.57,3.72,14.27,2.09,1.50,4.36,0.66,P<0.05).Conclusion The incidence of occupational injury is higher in shipbuilding and repairing industry,and fracture is the main type of occupational injury.The occurrence of occupational injury is affected by gender,age,smoking,working age,emotional state,health status and high temperature exposure.展开更多
Objective To understand the occurrence of cognitive impairment among residents in drinking water-borne endemic fluorosis(drinking water-borne fluorosis)areas,and to study its influencing factors.Methods In March 2023,...Objective To understand the occurrence of cognitive impairment among residents in drinking water-borne endemic fluorosis(drinking water-borne fluorosis)areas,and to study its influencing factors.Methods In March 2023,a cluster sampling method was used to select local residents aged 18 and above from the drinking water-borne fluorosis areas in Jishan County,Shanxi Province as survey subjects.展开更多
ObjectiveToinvestigatethe interactionof workplace noise,body mass index(BMI)and systemic inflammatory response on hypertension.Methods In January 2019,1124 male workers from an automobile factory in Wuhan were selecte...ObjectiveToinvestigatethe interactionof workplace noise,body mass index(BMI)and systemic inflammatory response on hypertension.Methods In January 2019,1124 male workers from an automobile factory in Wuhan were selected by cluster random sampling method.The study population was divided into normal body weight group(BMI<24 kg/m^(2))and overweight group(BMI≥24 kg/m^(2))according to BMI,and were followed up for 3 years.The occupational health examination of the workers was carried out every year,blood routine and blood biochemical indexes were collected,and the information of the workers'age,BMI,type of work and age of exposure to injury were collected through field questionnaires.The noise intensity of the workplace of theenterpriseewas measured for 3 consecutive years,and the equivalent sound level was calculated according to the working time.Normal and skewness measurements were described by Mean±SD and[M(Q_(1),Q_(3))],respectively.t-test or Wilcoxon rank sumtestwasusedfor inter-group comparisons.Categorical variables were expressed by frequency and percentage(%),and Chi-square test was used for intergroup comparisons.Mixed effects models and generalized estimationequations were fitted toanalyzethe relationshipbetween occupational noise,systemic inflammation,and their interactionterms with blood pressure and hypertensionrisk.Results Univariate analysis revealed that the white blood cell counts,neutrophil counts,lymphocyte counts and eosinophil counts were positively associated with systolic blood pressure and diastolic blood pressure in overweight group(n=467),respectively(P<0.05).The participants with white blood cell counts≥5.94×10^(9)/L,neutrophil counts≥3.31×10^(9)/L,lymphocyte counts≥2.03×10^(9)/L,and eosinophil counts≥0.12×10^(9)/L had increased risk of hypertension by 52%(RR=1.52,95%CI:1.11-2.05),37%(RR=1.37,95%CI:1.01-1.83),58%(RR=1.58,95%CI:1.18-2.09),and 52%(RR=1.52,95%CI:1.12-2.06),respectively(all P<0.05).Multivariate analysis found a positive association between BMI and the risk of hypertension in the overweight group(P<0.05),the participants with lymphocyte counts≥2.03×10^(9)/L and eosinophil counts≥0.12×10^(9)/L had increased risk of hypertension by 39%(RR=1.39,95%CI:1.01-1.89)and 46%(RR=1.46,95%CI:1.06-1.98),respectively(all P<0.05).There was no correlation between BMI and the risk of hypertension in normal weight group(P>0.05).The multiplicative interaction of occupational noise(≥80 dB)with white blood cell counts(≥5.94×10^(9)/L)and lymphocyte counts(≥2.03×10^(9)/L)increased the risk of hypertension by 100%(RR=2.00,95%CI:1.06-3.55)and 89%(RR=1.89,95%CI:1.01-3.32)(all P<0.05)in overweight group,respectively.Additionally,a significant additive interaction was observed between noise exposure(≥80 dB)and basophil counts(≥0.03×10^(9)/L)on hypertension risk in the overweight group(RERI=0.49,95%CI:0.02-0.96,P<0.05).Conclusion The combined exposure of occupational noise and systemic inflammation may increase the risk of hypertension in overweight workers in automobile manufacturing plants,and the two have additive and multiplicative interactions.展开更多
Introduction:To evaluate the effectiveness of tobacco control efforts,we conducted a comprehensive analysis of trends in smoking cessation willingness and behavior among Chinese smokers from 2010 to 2024.Methods:Data ...Introduction:To evaluate the effectiveness of tobacco control efforts,we conducted a comprehensive analysis of trends in smoking cessation willingness and behavior among Chinese smokers from 2010 to 2024.Methods:Data were obtained from the 2010 Global Adult Tobacco Survey(GATS)-China Project and the National Adult Tobacco Survey(NATS)conducted in 2018,2022,and 2024.All surveys employed multistage stratified cluster random sampling of the Chinese population aged 15 years and above.Complex sampling analysis was performed for calculations,and trend analysis was conducted using the Cochran-Armitage trend test.Results:From 2010 to 2024,cessation behavior among Chinese smokers increased significantly.Cessation rates rose from 16.88%to 22.65%,and the proportion of smokers who attempted to quit in the past 12 months increased from 14.37%to 24.75%.The proportion of smokers planning to quit within 12 months increased from 16.10%to 21.61%from 2010 to 2022,but dropped to 16.07%in 2024.Over the 14-year period,cessation rates and quit attempts increased significantly across almost all demographic groups.However,from 2022 to 2024,cessation rates among daily smokers declined while the proportion of those willing to quit decreased.Occasional smokers consistently demonstrated higher cessation rates,quit attempts,and willingness to quit compared to daily smokers.Conclusions:The observed increases in cessation behavior may be attributed to expanded smoking cessation services and extensive cessation campaigns implemented over the years.Enhanced cessation interventions should be targeted toward daily smokers.Pricing policies,graphic health warnings on packaging,and community-based comprehensive smoking cessation interventions can further enhance smokers’willingness to quit and encourage more cessation attempts.展开更多
Objective:To compare the adverse maternal and neonatal outcomes of multiple pregnancy and singleton pregnancy from multiple medical centers in Beijing.Methods:Data concerning maternal and neonatal adverse outcomes in ...Objective:To compare the adverse maternal and neonatal outcomes of multiple pregnancy and singleton pregnancy from multiple medical centers in Beijing.Methods:Data concerning maternal and neonatal adverse outcomes in multiple and singleton pregnancies were collected from 15 hospitals in Beijing by a systemic cluster sampling survey conducted from 20 June to 30 November 2013.The SPSS software (version 20.0) was used for data analysis.The x2 test was used tbr statistical analyses.Results:The rate of caesarean deliveries was much higher in women with multiple pregnancies (85.8％) than that in women with singleton pregnancies (42.6％,X2 =190.8,P ＜ 0.001).The incidences of anemia (X2 =40.023,P ＜ 0.001),preterm labor (X2 =1021.172,P ＜ 0.001),gestational diabetes mellitus (X2 =9.311,P ＜ 0.01),hypertensive disorders (X2 =122.708,P ＜ 0.001)and post-partum hemorrhage (X2-48.550,P ＜ 0.001) was significantly increased with multiple pregnancy.In addition,multiple pregnancy was associated with a significantly higher rate of small-for-gestational-age infants (X2 =92.602,P ＜ 0.001),low birth weight (X2 =1141.713,P ＜ 0.001),and neonatal intensive care unit (NICU) admission (X2 =340.129,P＜ 0.001).Conclusions:Multiple pregnancy is a significant risk factor for adverse maternal and neonatal outcomes in Beijing.Improving obstetric care for multiple pregnancy,particularly in reducing preterm labor,is required to reduce the risk to mothers and infants.展开更多
To estimate unknown population parameters based on panel data having nonignorable item nonresponse,we propose an innovative data grouping approach according to the number of observed components in the multivariate out...To estimate unknown population parameters based on panel data having nonignorable item nonresponse,we propose an innovative data grouping approach according to the number of observed components in the multivariate outcome y when the joint distribution of y and asso-ciated covariate x is nonparametric and the nonresponse probability conditional on y and x has a parametric form.To deal with the identifiability issue,we utilise a nonresponse instrument 2,an auxiliary variable related to y but not related to the nonresponse probability conditional ony and x.We apply a modified generalised method of moments to obtain estimators of the param-eters in the nonresponse probability,and a generalised regression estimation to utilise covariate information for efficient estimation of population parameters.Consistency and asymptotic nor-mality of the proposed estimators of the population parameters are established.Simulation and real data results are presented.展开更多
文摘This paper introduces the principle of PPS-based adaptive cluster sampling method and its modified HH estimator and HT estimator calculation method. It compares PPS-based adaptive cluster sampling method with SRS sampling and SRS-based adaptive group. The difference between the group sampling and the advantages and scope of the PPS adaptive cluster sampling method are analyzed. According to the case analysis, the relevant conclusions are drawn: 1) The adaptive cluster sampling method is more accurate than the SRS sampling;2) SRS adaptive The HT estimator of the cluster sampling is more stable than the HH estimator;3) The two estimators of the PPS adaptive cluster sampling method have little difference in the estimation of the population mean, but the HT estimator variance is smaller and more suitable;4) PPS The HH estimator of adaptive cluster sampling is the same as the HH estimator of SRS adaptive cluster sampling, but the variance is larger and unstable.
文摘If the population is rare and clustered,then simple random sampling gives a poor estimate of the population total.For such type of populations,adaptive cluster sampling is useful.But it loses control on the final sample size.Hence,the cost of sampling increases substantially.To overcome this problem,the surveyors often use auxiliary information which is easy to obtain and inexpensive.An attempt is made through the auxiliary information to control the final sample size.In this article,we have proposed two-stage negative adaptive cluster sampling design.It is a new design,which is a combination of two-stage sampling and negative adaptive cluster sampling designs.In this design,we consider an auxiliary variablewhich is highly negatively correlatedwith the variable of interest and auxiliary information is completely known.In the first stage of this design,an initial random sample is drawn by using the auxiliary information.Further,using Thompson’s(JAmStat Assoc 85:1050-1059,1990)adaptive procedure networks in the population are discovered.These networks serve as the primary-stage units(PSUs).In the second stage,random samples of unequal sizes are drawn from the PSUs to get the secondary-stage units(SSUs).The values of the auxiliary variable and the variable of interest are recorded for these SSUs.Regression estimator is proposed to estimate the population total of the variable of interest.A new estimator,Composite Horwitz-Thompson(CHT)-type estimator,is also proposed.It is based on only the information on the variable of interest.Variances of the above two estimators along with their unbiased estimators are derived.Using this proposed methodology,sample survey was conducted at Western Ghat of Maharashtra,India.The comparison of the performance of these estimators and methodology is presented and compared with other existing methods.The cost-benefit analysis is given.
文摘Adaptive cluster sampling （ACS） has been widely used for data collection of environment and natural resources. However, the randomness of its final sample size often impedes the use of this method. To control the final sample sizes, in this study, a k-step ACS based on Horvitz-Thompson （HT） estimator was developed and an unbiased estimator was derived. The k-step ACS-HT was assessed first using a simulated example and then using a real survey for numbers of plants for three species that were characterized by clustered and patchily spatial distributions. The effectiveness of this sampling design method was assessed in comparison with ACS Hansen-Hurwitz （ACS-HH） and ACS- HT estimators, and k-step ACS-HT estimator. The effectiveness of using different k- step sizes was also compared. The results showed that k-step ACS^HT estimator was most effective and ACS-HH was the least. Moreover, stable sample mean and variance estimates could be obtained after a certain number of steps, but depending on plant species, k-step ACS without replacement was slightly more effective than that with replacement. In k-step ACS, the variance estimate of one-step ACS is much larger than other k-step ACS （k 〉 1）, but it is smaller than ACS. This implies that k-step ACS is more effective than traditional ACS, besides, the final sample size can be controlled easily in population with big clusters.
基金supported by the National Key R&D Program of China(2020YFC2003102).
文摘Objective:To reveal the distribution characteristics and demographic factors of traditional Chinese medicine(TCM)constitution among elderly individuals in China.Methods: Elderly individuals from seven regions in China were selected as samples in this study using a multistage cluster random sampling method.The basic information questionnaire and Constitution in Chinese Medicine Questionnaire(Elderly Edition)were used.Descriptive statistical analysis,chi-squared tests,and binary logistic regression analysis were used.Results: The single balanced constitution(BC)accounted for 23.9%.The results of the major TCM constitution types showed that BC(43.2%)accounted for the largest proportion and unbalanced constitutions ranged from 0.9%to 15.7%.East China region(odds ratio[OR]=2.097;95%confidence interval[CI],1.912 to 2.301),married status(OR=1.341;95%CI,1.235 to 1.457),and managers(OR=1.254;95%CI,1.044 to 1.505)were significantly associated with BC.Age>70 years was associated with qi-deficiency constitution and blood stasis constitution(BSC).Female sex was significantly associated with yang-deficiency constitution(OR=1.646;95%CI,1.52 to 1.782).Southwest region was significantly associated with phlegm-dampness constitution(OR=1.809;95%CI,1.569 to 2.086).North China region was significantly associated with inherited special constitution(OR=2.521;95%CI,1.569 to 4.05).South China region(OR=2.741;95%CI,1.997 to 1.3.763),Central China region(OR=8.889;95%CI,6.676 to 11.835),senior middle school education(OR=2.442;95%CI,1.932 to 3.088),and managers(OR=1.804;95%CI,1.21 to 2.69)were significantly associated with BSC.Conclusions: This study defined the distribution characteristics and demographic factors of TCM constitution in the elderly population.Adjusting and improving unbalanced constitutions,which are correlated with diseases,can help promote healthy aging through the scientific management of these demographic factors.
文摘This work was carried out with the objective of proposing some changes in the Strand’s sampling method, in which the trees are selected in sampling units with probability proportional to its diameter for the calculation of the stand density and basal area, and proportional to its height for the calculation of volume per hectare. Data used to evaluate the efficiency of the sampling of Strand in clusters were collected in stands of Pinus elliottii Engelm, located in a National Forest, Rio Grande do Sul State, Brazil. In the course of this research work it was proposed to convert the sampling unit into a cluster, structurally more efficient to obtain consistent estimates of volume and of dominant heights, using volumetric equivalence, which results in a form factor equal to one for the final calculation of volume per hectare and an indirect method to obtain the average height of Lorey. The objectives of this study were achieved, because with this methodology it is not necessary to measure heights of trees in the sampling unit, except a dominant height by cluster to evaluate sites. The development of independent estimators for basal area and volume gave rise to the proposition of an estimator for average height of Lorey, but without measuring any tree height in the sampling. The proposed methodology is an attractive solution to reduce costs in forest inventories, with the ability to have greater accuracy and scope for information at the level of compartments, without increasing the cost of sampling in comparison to that performed with units of fixed area. The use of smaller permanent sampling units with higher intensity in the compartments before the final cut will substantially increase the precision of the estimators in these management units, which will enable them to eliminate the pre-cut inventory in forest enterprises.
基金National Key R&D Program of China(No.2016YFB1001401)
文摘Aiming at the diversity of hand gesture traces by different people,the article presents novel method called cluster dynamic time warping( CDTW),which is based on the main axis classification and sample clustering of individuals. This method shows good performance on reducing the complexity of recognition and strong robustness of individuals. Data acquisition is implemented on a triaxial accelerometer with 100 Hz sampling frequency. A database of 2400 traces was created by ten subjects for the system testing and evaluation. The overall accuracy was found to be 98. 84% for user independent gesture recognition and 96. 7% for user dependent gesture recognition,higher than dynamic time warping( DTW),derivative DTW( DDTW) and piecewise DTW( PDTW) methods.Computation cost of CDTW in this project has been reduced 11 520 times compared with DTW.
基金supported in part by the National Natural Science Foundation of China under Grant U22A2055in part by the Liaoning Revitalization Talents Program under Grant XLYC2002032.
文摘The power transformer is the core equipment of a power system,and its reliable operation is crucial for maintaining the safety and stability of power grids.Dissolved gases in insulating oil are an important information source for analyzing transformer operating status and fault diagnosis.At present,intelligent fault diagnosis methods for power transformers are mostly based on classification algorithms,but the diagnosis models may be relatively complicated.Some models have poor generalization ability when training samples are scarce.Clustering algorithms can better deal with this problem.Fault diagnosis of transformers based on a clustering algorithm primarily utilizes the proportional data of dissolved gases as features,which have not considered abundant gas ratio features,and those clustering methods are prone to invalid clustering.In order to solve those problems,this paper uses more features as information sources of power transformer diagnosis based on clustering method.Different clustering spaces are considered for different fault types.Clustering centers are found on samples with the same fault type,which aims to expand the data distribution difference in different fault types.This paper also uses genetic algorithm(GA)to optimize multiple data clustering spaces and improve clustering effect.Based on multiple data sets,it is verified that the proposed method can effectively avoid the occurrence of invalid clustering,and the difference among different fault types based on multiple clustering spaces method is more obvious.
文摘Coverage of nominal 95% confidence intervals of a proportion estimated from a sample obtained under a complex survey design, or a proportion estimated from a ratio of two random variables, can depart significantly from its target. Effective calibration methods exist for intervals for a proportion derived from a single binary study variable, but not for estimates of thematic classification accuracy. To promote a calibration of confidence intervals within the context of land-cover mapping, this study first illustrates a common problem of under and over-coverage with standard confidence intervals, and then proposes a simple and fast calibration that more often than not will improve coverage. The demonstration is with simulated sampling from a classified map with four classes, and a reference class known for every unit in a population of 160,000 units arranged in a square array. The simulations include four common probability sampling designs for accuracy assessment, and three sample sizes. Statistically significant over- and under-coverage was present in estimates of user’s (UA) and producer’s accuracy (PA) as well as in estimates of class area proportion. A calibration with Bayes intervals for UA and PA was most efficient with smaller sample sizes and two cluster sampling designs.
基金Funded by the R & D Project of the Ministry of Construction of China.
文摘This paper describes a structural equation modeling （SEM） analysis of factors influencing architects＇ trust in project design teams. We undertook a survey of architects, during which we distributed 193 questionnaires in 29 A-level architectural design institutes selected radomly from the altogether 59 ones in Shenzhen, P. R. China, and received 130 valid questionnaires. We used Amos 6.0 for SEM to identify significant personal construct based factors affecting interpersonal trust. The results show that only social interaction between architects significantly affects their interpersonal trust. The explained variance of trus~ is not very high in the model. Therefore, future research should add more factors into the current model. The practical implication is that team managers should promote the social interactions between team members such that the interpersonal trust level between team members can be improved.
基金the financial support of the Center of Excellence,University of Tehran for this research
文摘Fast growing poplar species enjoy a highly favored position in Iran’s forest product industries. However, information on poplar plantations, such as areas, growing stock and harvest volumes, are largely obtained by non scientific means and poorly executed methods. A few studies have been conducted to obtain data on the capacity of poplar plantations, their extent, existing growing stock, distribution and species choice in three provinces, i.e., Western Azerbaijan, Kurdistan and Hamedan, with relatively well developed management systems. We opted for a cluster method, a standard sampling method for conducting similar investigations, consisting of two phases. In the first phase we collected library information and conducted half-open interviews with villagers. In the second phase field measurements in the villages of these three provinces were carried out. Information from field measurements on growing stock, cultivated areas, dominant species were used to estimate volumes by way of volume and weight tables. Results obtained from the present study indicate that the average annual volume of timber harvested in the three provinces was 697,723 m3, with an average sampling error of 22.7 per cent. This annual volume of poplar timber harvested from the three provinces was estimated to amount to about 25 per cent of overall harvest; at that rate, the overall annual utilization potential of poplar plantations will be 10 million m3, which constitutes a reliable resource of raw timber for use in wood and paper industries.
文摘Background: The World Health Organization (WHO) initiated the Expanded Program on Immunization (EPI) in 1974. It has been widely used in different studies. Along with this, other survey methodologies have been compared to study immunization coverage at different regions. To consider different survey methodologies, one of the most important factors is the cost incurred that survey methodology. A survey method is considered as more efficient or better than the other survey method if the cost incurred in a particular method is less than the other one. Methods: In this study, cost incurred in two stage (30 × 30) cluster sampling and systematic sampling methods have been compared using a cost function for measles vaccine coverage. Measles vaccine coverage data has been taken from the survey “Comparison of Two Survey Methodologies to Estimates Total Vaccination Coverage” sponsored by Indian Council of Medical Research (ICMR), New Delhi. Results: The results show that there are no significant differences between the point estimates of measles vaccine coverage under the considered survey methodologies. But the cost incurred in systematic sampling is more than that of two stage cluster sampling. Conclusion: It can be concluded that systematic sampling survey is costlier than that of two stage cluster sampling for this study population.
文摘Objective To understand the occupational injury situation of front-line workers in metallurgical and shipbuilding and repairing industry,and explore the risk factors of occupational injury.Methods From September 2023 to March 2024,using cluster sampling method,front-line workers from 2 metallurgical enterprises in Shaoguan and Jinan City and 2 shipbuildinggand repairing enterprises in Jiangmen and Shenzhen City were selected as the investigation objects.6248 questionnaires were distributed and collected,and 6178 were effective questionnaires,with a effective recovery rate of 98.88%.The basic information,living habits,working system,protection and occupational injury of workers were investigated,and the data of occupational injury in factories was collected.The types,jobs and main causes of occupational injuries in different industries were analyzed,and the influencing factors of occupational injuries were analyzed by univariate and multi-factor logistic regression.Results The incidence of occupational injury was 3.13%(128/4086)in metallurgical industry and 4.02%(84/2092)in shipbuilding and repairing industry.The top three occupational injuries in the metallurgical industry were furnace worker(17.19%,22/128),steel rolling worker(14.84%,19/128),maintenance worker(10.16%,13/128),and the top three injury types were mechanical injury(24.22%,31/128),height fall(20.31%,26/128)and object strikes(17.97%,23/128).The top three occupational injuries in shipbuilding and repairing industry were welder(20.24%,17/84),riveter(9.52%,8/84)and crane(8.33%,7/84).The top three injury types were hit by objects(34.52%,29/84),hit by falling objects(22.62%,19/84),and lifting injury(20.24%,17/84).The injuries of workers in metallurgical industry and shipbuilding and repairing industry weremainly fractures,accounting for 32.03%(41/128)and 60.71%(51/84),respectively.The incidence of occupational injury was higher in males,with sleep disorder,high temperature exposure and chemical toxicity exposure(P<0.05).There were significant differences in age,smoking degree,working age and emotional state between workers with occupational injury and those without occupational injury(P<0.05).Multivariate analysis showed that male,age above 50 years old,moderate smoking,working years of 5-9 years,mild anxiety,poor health status and high temperature exposure were risk factors for occupational injury(0R=25.57,3.72,14.27,2.09,1.50,4.36,0.66,P<0.05).Conclusion The incidence of occupational injury is higher in shipbuilding and repairing industry,and fracture is the main type of occupational injury.The occurrence of occupational injury is affected by gender,age,smoking,working age,emotional state,health status and high temperature exposure.
文摘Objective To understand the occurrence of cognitive impairment among residents in drinking water-borne endemic fluorosis(drinking water-borne fluorosis)areas,and to study its influencing factors.Methods In March 2023,a cluster sampling method was used to select local residents aged 18 and above from the drinking water-borne fluorosis areas in Jishan County,Shanxi Province as survey subjects.
文摘ObjectiveToinvestigatethe interactionof workplace noise,body mass index(BMI)and systemic inflammatory response on hypertension.Methods In January 2019,1124 male workers from an automobile factory in Wuhan were selected by cluster random sampling method.The study population was divided into normal body weight group(BMI<24 kg/m^(2))and overweight group(BMI≥24 kg/m^(2))according to BMI,and were followed up for 3 years.The occupational health examination of the workers was carried out every year,blood routine and blood biochemical indexes were collected,and the information of the workers'age,BMI,type of work and age of exposure to injury were collected through field questionnaires.The noise intensity of the workplace of theenterpriseewas measured for 3 consecutive years,and the equivalent sound level was calculated according to the working time.Normal and skewness measurements were described by Mean±SD and[M(Q_(1),Q_(3))],respectively.t-test or Wilcoxon rank sumtestwasusedfor inter-group comparisons.Categorical variables were expressed by frequency and percentage(%),and Chi-square test was used for intergroup comparisons.Mixed effects models and generalized estimationequations were fitted toanalyzethe relationshipbetween occupational noise,systemic inflammation,and their interactionterms with blood pressure and hypertensionrisk.Results Univariate analysis revealed that the white blood cell counts,neutrophil counts,lymphocyte counts and eosinophil counts were positively associated with systolic blood pressure and diastolic blood pressure in overweight group(n=467),respectively(P<0.05).The participants with white blood cell counts≥5.94×10^(9)/L,neutrophil counts≥3.31×10^(9)/L,lymphocyte counts≥2.03×10^(9)/L,and eosinophil counts≥0.12×10^(9)/L had increased risk of hypertension by 52%(RR=1.52,95%CI:1.11-2.05),37%(RR=1.37,95%CI:1.01-1.83),58%(RR=1.58,95%CI:1.18-2.09),and 52%(RR=1.52,95%CI:1.12-2.06),respectively(all P<0.05).Multivariate analysis found a positive association between BMI and the risk of hypertension in the overweight group(P<0.05),the participants with lymphocyte counts≥2.03×10^(9)/L and eosinophil counts≥0.12×10^(9)/L had increased risk of hypertension by 39%(RR=1.39,95%CI:1.01-1.89)and 46%(RR=1.46,95%CI:1.06-1.98),respectively(all P<0.05).There was no correlation between BMI and the risk of hypertension in normal weight group(P>0.05).The multiplicative interaction of occupational noise(≥80 dB)with white blood cell counts(≥5.94×10^(9)/L)and lymphocyte counts(≥2.03×10^(9)/L)increased the risk of hypertension by 100%(RR=2.00,95%CI:1.06-3.55)and 89%(RR=1.89,95%CI:1.01-3.32)(all P<0.05)in overweight group,respectively.Additionally,a significant additive interaction was observed between noise exposure(≥80 dB)and basophil counts(≥0.03×10^(9)/L)on hypertension risk in the overweight group(RERI=0.49,95%CI:0.02-0.96,P<0.05).Conclusion The combined exposure of occupational noise and systemic inflammation may increase the risk of hypertension in overweight workers in automobile manufacturing plants,and the two have additive and multiplicative interactions.
基金Supported by National Major Scientific and Technological Special Project(2023ZD0506401)Global Health Capacity Building and Tobacco Control Project,Chinese Center for Disease Control and Prevention(2025).
文摘Introduction:To evaluate the effectiveness of tobacco control efforts,we conducted a comprehensive analysis of trends in smoking cessation willingness and behavior among Chinese smokers from 2010 to 2024.Methods:Data were obtained from the 2010 Global Adult Tobacco Survey(GATS)-China Project and the National Adult Tobacco Survey(NATS)conducted in 2018,2022,and 2024.All surveys employed multistage stratified cluster random sampling of the Chinese population aged 15 years and above.Complex sampling analysis was performed for calculations,and trend analysis was conducted using the Cochran-Armitage trend test.Results:From 2010 to 2024,cessation behavior among Chinese smokers increased significantly.Cessation rates rose from 16.88%to 22.65%,and the proportion of smokers who attempted to quit in the past 12 months increased from 14.37%to 24.75%.The proportion of smokers planning to quit within 12 months increased from 16.10%to 21.61%from 2010 to 2022,but dropped to 16.07%in 2024.Over the 14-year period,cessation rates and quit attempts increased significantly across almost all demographic groups.However,from 2022 to 2024,cessation rates among daily smokers declined while the proportion of those willing to quit decreased.Occasional smokers consistently demonstrated higher cessation rates,quit attempts,and willingness to quit compared to daily smokers.Conclusions:The observed increases in cessation behavior may be attributed to expanded smoking cessation services and extensive cessation campaigns implemented over the years.Enhanced cessation interventions should be targeted toward daily smokers.Pricing policies,graphic health warnings on packaging,and community-based comprehensive smoking cessation interventions can further enhance smokers’willingness to quit and encourage more cessation attempts.
文摘Objective:To compare the adverse maternal and neonatal outcomes of multiple pregnancy and singleton pregnancy from multiple medical centers in Beijing.Methods:Data concerning maternal and neonatal adverse outcomes in multiple and singleton pregnancies were collected from 15 hospitals in Beijing by a systemic cluster sampling survey conducted from 20 June to 30 November 2013.The SPSS software (version 20.0) was used for data analysis.The x2 test was used tbr statistical analyses.Results:The rate of caesarean deliveries was much higher in women with multiple pregnancies (85.8％) than that in women with singleton pregnancies (42.6％,X2 =190.8,P ＜ 0.001).The incidences of anemia (X2 =40.023,P ＜ 0.001),preterm labor (X2 =1021.172,P ＜ 0.001),gestational diabetes mellitus (X2 =9.311,P ＜ 0.01),hypertensive disorders (X2 =122.708,P ＜ 0.001)and post-partum hemorrhage (X2-48.550,P ＜ 0.001) was significantly increased with multiple pregnancy.In addition,multiple pregnancy was associated with a significantly higher rate of small-for-gestational-age infants (X2 =92.602,P ＜ 0.001),low birth weight (X2 =1141.713,P ＜ 0.001),and neonatal intensive care unit (NICU) admission (X2 =340.129,P＜ 0.001).Conclusions:Multiple pregnancy is a significant risk factor for adverse maternal and neonatal outcomes in Beijing.Improving obstetric care for multiple pregnancy,particularly in reducing preterm labor,is required to reduce the risk to mothers and infants.
基金The authors’research was partially supported by the National Natural Science Foundation of China grant 11831008the U.S.National Science Foundation grant DMS-1914411.
文摘To estimate unknown population parameters based on panel data having nonignorable item nonresponse,we propose an innovative data grouping approach according to the number of observed components in the multivariate outcome y when the joint distribution of y and asso-ciated covariate x is nonparametric and the nonresponse probability conditional on y and x has a parametric form.To deal with the identifiability issue,we utilise a nonresponse instrument 2,an auxiliary variable related to y but not related to the nonresponse probability conditional ony and x.We apply a modified generalised method of moments to obtain estimators of the param-eters in the nonresponse probability,and a generalised regression estimation to utilise covariate information for efficient estimation of population parameters.Consistency and asymptotic nor-mality of the proposed estimators of the population parameters are established.Simulation and real data results are presented.
