• Journal of the Korean Statistical Society
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• 제27권4호
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• pp.459-469
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• 1998

Balanced half sample method is a simple variance estimation method for complex sampling designs. Since it is simple and flexible, it has been widely used in large scale sample surveys. However, the usual BHS method overestimate the true variance in without replacement sampling and two-stage cluster sampling. Focusing on this point , we proposed an unbiased BHS variance estimator in a stratified two-stage cluster sampling and then described an implementation method of the proposed estimator. Finally, partially BHS design is explained as a tool of reducing the number of replications of the proposed estimator.

• Communications for Statistical Applications and Methods
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• 제5권1호
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• pp.107-120
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• 1998

This research aims here to develop a certain extended double sampling plan, EDS, which is an extension of ordinary double sampling plan in the sense that the second-stage sampling effort and second-stage critical value are allowed to depend on the point at which the first-stage continuation region is traversed. For purpose of comparison, single sampling plan, optimal ordinary double sampling plan(ODS) and sequential probability ratio test are considered with the same overall error rates, respectively. It is observed that the EDS idea allows less sampling effort than the optimal ODS.

• Journal of applied mathematics & informatics
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• 제3권1호
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• pp.101-115
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• 1996

In this paper we extend the best choice of subsample size m in the 2-stage sampling which suggested by Mohammad(1986) to the 3-stage sampling in cases of known and of unknown cost and variance ratio. We find the subsample size m.k which ensures more than the relative efficiency 90% Also we see that the choice of 3-stage subsample size depends on the design parameters using in 2-stage sampling.

• 한국산림과학회지
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• 제65권1호
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• pp.68-73
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• 1984

Simple random sampling과 P.P.S. sampling의 효율을 비교하기 위하여 오스트리아 Salzburg 부근의 침엽수 장령림 임분에서 임목조사를 실시하였다. 축적 1:10,000의 흑백 적외선 사진을 판독하여, 조사 임지를 제지, 유령림, 너도 밤나무 장령림, 침엽수 장령림으로 구분하고, 침엽수 장령림 내에서 random sampling에 의한 99개의 표본점과 P.P.S. sampling에 의한 75개의 표본점을 흉고 단면적 제수 4인 Relascope에 의하여 야외 조사한 자료를 비교한 결과는 다음과 같다. 1) random sampling에 의한 임분 재적의 추정치는 $422.0m^3/ha$이었고, P.P.S. sampling에 의해서는 $433.5m^3/ha$이었으나 이들간의 통계적 유의성은 없었다. 2) 5 %의 허용 오차내에서는 P.P.S. sampling에 의하여는 170점, random sampling에 의하여는 237점이 필요하였다. 3) P.P.S. sampling은 random sampling에 비하여 야외 조사 시간을 17% 감소시킬 수 있었다.

• Smart Structures and Systems
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• 제17권4호
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• pp.647-667
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• 2016

In this paper, dynamic displacement is estimated with high accuracy by blending high-sampling rate acceleration data with low-sampling rate displacement measurement using a two-stage Kalman estimator. In Stage 1, the two-stage Kalman estimator first approximates dynamic displacement. Then, the estimator in Stage 2 estimates a bias with high accuracy and refines the displacement estimate from Stage 1. In the previous Kalman filter based displacement techniques, the estimation accuracy can deteriorate due to (1) the discontinuities produced when the estimate is adjusted by displacement measurement and (2) slow convergence at the beginning of estimation. To resolve these drawbacks, the previous techniques adopt smoothing techniques, which involve additional future measurements in the estimation. However, the smoothing techniques require more computational time and resources and hamper real-time estimation. The proposed technique addresses the drawbacks of the previous techniques without smoothing. The performance of the proposed technique is verified under various dynamic loading, sampling rate and noise level conditions via a series of numerical simulations and experiments. Its performance is also compared with those of the existing Kalman filter based techniques.

• 품질경영학회지
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• 제21권1호
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• pp.35-43
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• 1993

The principal objective of a sampling plan is to make efficient use of the budget allocated and to obtain as precise an estimate of a population parameter as possible. In order to estimate the proportion of defectives produced or to determine some measure of product Quality, it is necessary to select random samples which represent a population parameter of the process. In this case, the two stage sampling is more efficient and convenient than simple random sampling. Therefore this paper aims to propose the design procedures of two stage sampling plan to obtain a representative samples in considering the sampling precision under the restricted sampling unspection cost.

• 응용통계연구
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• 제13권2호
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• pp.207-224
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• 2000

모집단을 집략화하여 층화 2-단 표본 추출을 할 때에 일반적으로 집락의 크기는 정해져 있다. 그러나 집락이 아파트 단지 등과 같은 경우에 집락의 크기는 큰 차이를 보인다. 이 경우 집락을 합치거나 또는 분할할 필요가 생긴다. 대 표본조사(large sample survey)에서 행정상 또는 조사 편의상 동질의 원소들이 집락화 되어 있고 집락의 크기를 결정할 필요가 있을 경우가 고려되었으며 본 논문에서는 집락의 최적크기를 결정하는 문제를 다루었다. 또한 주어진 비용 하에서 최적의 일차 추출 단위 수와 최적의 이차 추출 단위 수를 구하였다.

• Journal of the Korean Data and Information Science Society
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• 제14권4호
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• pp.1067-1082
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• 2003

In this paper, we propose a randomized response model with discrete quantitative attribute by three-stage cluster sampling for obtaining discrete quantitative data by using the Liu & Chow model(1976), when the population was made up of sensitive discrete quantitative clusters. We obtain the minimum variance by calculating the optimum number of fsu, ssu, tsu under the some given constant cost. And we obtain the minimum cost under the some given accuracy.

• 응용통계연구
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• 제24권2호
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• pp.393-400
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• 2011

조사비용과 시간과 같은 현실적인 제약하에서 관측단위 (observation unit)의 집합인 집락(cluster)율 추출하는 집락추출법은 대부분의 대형조사(large scale survey) 에서 흔히 사용된다. 특별히 집락내의 관측단위가 매우 유사한 경우, 집락 내의 모든 관측치를 조사하는 대신 일부를 추출하여 조사하는 이단계 집락 추출법이 선호된다. 이단계 집락추출법의 적용시 집락인 1차추출단위 (Primary Sampling Unit; PSU)와 관측단위인 2차추출단위(Secondary Sampling Unit; SSU)의 표본수 결정은 주어진 비용과 표본으로부터 계산되어지는 통계량의 정도에 의존한다. 본 연구에서는 기존의 1차추출단위의 크기가 동일하다는 가정하에서 유도된 최적 PSU와 SSU 표본크기 산출과정을 일반화하여 1차추출단위의 크기가 같지 않을 경우의 최적 표본크기를 유도하고 그 결과를 제 4차 퇴원환자조사를 위한 표본추출 방안에 적용하여 기존방법과 비교하였으며 이를 바탕으로 제 7차 퇴원환자조사를 위한 표본크기를 제안하였다.

• Communications for Statistical Applications and Methods
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• 제17권1호
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• pp.89-98
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• 2010

In this paper, a two-stage group sampling plan based on the time truncated life test is proposed for the Weibull distribution. The design parameters such as the number of groups and the acceptance number in each stage are determined by satisfying the producer's and consumer's risks simultaneously when the group size and the test duration are specified. The acceptable reliability level is expressed by the ratio of the true mean life to the specified life. It was demonstrated from the comparison with single-stage group sampling plans that the proposed plan can reduce the average sample number or improve the operating characteristics.