• Journal of the Korean Data and Information Science Society
• /
• v.14 no.1
• /
• pp.55-65
• /
• 2003

In this study, we systemize the theoretical validity for applying unrelated question model to three-stage cluster sampling method and derive the estimate and it's variance of sensitive parameter. We derive the minimum variance form under the optimal values of the subsample sizes when the cost are fixed. Under the some given precision, we obtain the optimal values of the subsample sizes and derive the minimum cost form by using them.

• Proceedings of the Korean Statistical Society Conference
• /
• 2003.10a
• /
• pp.207-212
• /
• 2003

In this paper, we propose a class of imputed estimators using response probability. The proposed estimator can be justified under the response probability model and thus is robust against the failure of the assumed imputation model. We also propose a variance estimator that is justified under the response probability model.

• Proceedings of the Korean Statistical Society Conference
• /
• 2003.10a
• /
• pp.253-256
• /
• 2003

In ecological studies, animal science, or entomology, the variance of count is considered to have the power of the mean relationship with the mean count as Taylor (1961) presented his famous 'Taylor's Power Law'. In this talk, we are going to review the development of TPL and its extension toward pest management sampling scheme. Different estimation methods are compared. Quasilikelihood approach is suggested to incorporate covariate information. Possible extensions will be discussed.

• 한국해양학회지
• /
• v.24 no.4
• /
• pp.165-171
• /
• 1989

To examine the sample variability of zooplankton, samples were collected at two stations in the nearshore off Anhung (Chungnam, Korea), using a NORPAC net (76 Cm diameter, 0.333 mm mesh size) for two days, April 5 and 6, 1989. The net was towed vertically to eliminate the source of variation due to vertical migration. During the period of 6 hours, triplicate sampling was done every one or two hour at each station. Species composition and abundances at two stations were not so different, but the abundances at each station varied greatly with respect to sampling time. Greater abundance at one sampling time ranged 2.3-8.7 times of smaller abundance at another sampling time. At the level of ${\alpha}=0.05$, however, mean abundances of different sampling time did not differ significantly from each other due to the large variance. It was believed that the large variance was caused by the time dependent effect of patchiness of which parameters were varied with time because of sea water movement. From the variation within the triplicate samples, it was considered that the abundance data obtained from single tow were not significantly different from the data in the range of 50-200% of those from single tow. From these results, the necessity for the replicate and time dependent sampling was indicated. In the nearshore like the sampling site of this study, it seemed to be better to reduce the number of stations for the replicate and time dependent sampling though the proper sampling scheme was to be decided based on the goal of the study.

• Journal of the Korean Statistical Society
• /
• v.32 no.2
• /
• pp.175-191
• /
• 2003

An empirical Bayesian approach is discussed for estimation of characteristics from the two-way balanced rotation sampling design which includes U.S. Current Population Survey and Canadian Labor Force Survey as special cases. An empirical Bayesian estimator is derived for monthly effect under presence of two types of biases and correlations It is shown that the marginal distribution of observation provides more general correlation structure than that frequentist has assumed. Consistent estimators are derived for hyper-parameters in Normal priors.

• Journal of the Korean Statistical Society
• /
• v.8 no.2
• /
• pp.165-168
• /
• 1979

For crops that are planted in a lattice layout, sampling designs can be made to take advantage of this regular arrangement. In order to select which tobacco plants to be examined in a survey to estimate disease loss in tobacco a method of, so called, bent plots was devised based on the regularity of plantings in the tobacco fields. We will first describe this sample selection and measurement method and then provide estimators and their bias and variance properties.

• Communications for Statistical Applications and Methods
• /
• v.8 no.3
• /
• pp.739-751
• /
• 2001

In this paper, a sample design is studied for 2000 forestry management survey of five types forestry , tree felling, gathering of pine mushroom, growing of nut trees, growing of wild flowers, and lumbering industry. We introduce population stratification and a modified stratified cut-off sampling which deal with determination of sample size, sample allocation, and estimation of total and variance of estimator. Substitution of sample units and imputation of nonresponse units are discussed for reducing the nonsampling errors.

• Communications for Statistical Applications and Methods
• /
• v.10 no.3
• /
• pp.665-678
• /
• 2003

In this paper we suggest the new calibration estimator, which is called to the recalibration estimator, and its variance estimator using two-phase sampling technique according to the auxiliary information having strong correlation with the variable of interest under the unit nonresponse. In this unit nonresponse situation, an available information may exists at the level of whole population or the first-phase sample. The proposed recalibration estimator derives from the first and second phase weights respectively.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05a
• /
• pp.462-465
• /
• 2006

This paper is aimed at proposing the sampling method to reduce variance of statistical parameters in uncertainty analysis of concrete structures. The proposed method is a modification of Latin Hypercube sampling method. This uses specially modified tables of random permutations of rank number. Also, the Spearman coefficient is used to make modified tables. Numerical analysis is carried out to predict the uncertainty of axial shortening in prestressed concrete bridge. The numerical results show that the method is efficient for uncertainty analysis of complex structural system such as prestressed concrete bridges.

• Communications for Statistical Applications and Methods
• /
• v.8 no.1
• /
• pp.257-269
• /
• 2001

The simulation is used to estimate an overflow probability in a stable parallel network with coupled inputs. Since the general simulation needs extremely many trials to obtain such a small probability, the fast simulation is proposed to reduce trials instead. By using the Cramer’s theorem, we first obtain an optimally changed measure under which the variance of the estimator is minimized. Then, we use it to derive an importance sampling estimator of the overflow probability which enables us to perform the fast simulation.