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Narges Najafi, Hossein Bevrani,
Volume 4, Issue 1 (9-2010)
Abstract
This paper is devoted to compute the sample size for estimation of Normal distribution mean with Bayesian approach. The Quadratic loss function is considered and three criterions are applied to obtain p- tolerance regions with the lowest posterior loss. These criterions are: average length, average coverage and worst outcome. The proposed methodology is examined, and its effectiveness is shown.
Zahra Yazari, Sayed Mohammad Reza Alavi,
Volume 8, Issue 2 (3-2015)
Abstract
The randomized response technique is a procedure for collecting the information on sensitive characteristics without exposing the identity of the respondent. Optional randomized response models are based on the basic premise that a question may be sensitive for one respondent but may not be sensitive for another. In this paper a three stage optional randomized response model is proposed and its properties are discussed using simulation with R package. The mean and sensitivity level of household's income of students of Shahid Chamran University are estimated using this model.
Sayed Mohammad Reza Alavi, Mahboobeh Tajadini,
Volume 9, Issue 2 (2-2016)
Abstract
In survey sampling, the respondents often do not state the actual response to the sensitive questions. Randomized response techniques have been designed to protect the privacy of responses. This paper focused on the randomized response technique for qualitative variables based on Simmons method. Using idea of repeating answer, the new repeated randomized response technique is introduced. Its efficiency is compared with the Simmons technique. Proportion of student cheating in Shahid Chamran University is estimated using the proposed technique.
Hamed Mohamadghasemi, Ehsan Zamanzade, Mohammad Mohammadi,
Volume 10, Issue 1 (8-2016)
Abstract
Judgment post stratification is a sampling strategy which uses ranking information to give more efficient statistical inference than simple random sampling. In this paper, we introduce a new mean estimator for judgment post stratification. The estimator is obtained by using ordering observations in post strata. Our simulation results indicate that the new estimator performs better than its leading competitors in the literature.
Mahtab Tarhani, Sayed Mohammad Reaz Alavi,
Volume 10, Issue 2 (2-2017)
Abstract
In weighted sampling as a generalization of random sampling, every observation, y, is recorded with probably proportional to a non-negative function of y. In this paper, the normal regression model is investigated under the weighted sampling for a common weight function. Parameters of the model are estimated for known and unknown weight parameters. Using simulation, efficiency of estimators is studied when they have not closed forms. As an application, the data of number of visited patients by specialist doctors in Social Security Organization of Ahvaz in Iran (SSOAI) are analyzed.
Mohamad Bayat, Hamzeh Torabi,
Volume 12, Issue 1 (9-2018)
Abstract
Nowadays, the use of various censorship methods has become widespread in industrial and clinical tests. Type I and Type II progressive censoring are two types of these censors. The use of these censors also has some disadvantages. This article tries to reduce the defects of the type I progressive censoring by making some change to progressive censorship. Considering the number and the time of the withdrawals as a random variable, this is done. First, Type I, Type II progressive censoring and two of their generalizations are introduced. Then, we introduce the new censoring based on the Type I progressive censoring and its probability density function. Also, some of its special cases will be explained and a few related theorems are brought. Finally, the simulation algorithm is brought and for comparison of introduced censorship against the traditional censorships a simulation study was done.
Sayed Mohammad Reza Alavi, Mohammad Joharzadeh, Rahim Chinipardaz,
Volume 13, Issue 1 (9-2019)
Abstract
Usually in survey sampling when the sensitive questions are asked directly, the respondents do not provide true answers. The randomized response techniques have been introduced to protect the privacy responses. In this article we focus on Simons randomized response technique for qualitative variables. Using the combination of the two different Simmons’ models, a new combined randomized response technique is introduced to increase protection of privacy. Using simulation in R package, efficiency of the proposed model is compared to the Simmons’ and Alavi and Tajodini's (1394) models. Finally, the proposed model has been employed for estimating the proportion of student cheating in Shahid Chamran University.
Pegah Afshin, Bardia Panahbehagh, Amir Hossein Sanatpour,
Volume 13, Issue 2 (2-2020)
Abstract
We introduce a modified Poisson sampling, with a fixed lower bound of sample size. The design is a combination of simple random sampling and Poisson sampling. Simple random sampling is used to compensate for the lack of sample size from remaining elements in the finite population, after execution of a
Poisson sampling. At the first stage, the units are sampled independently with given inclusion probabilities. But in the second stage, inclusion probabilities are dependent to each other. Because it is important to know, which of the elements are selected in the first stage and which of them are remained. Some advantages of our design are: simple performance, controlling sample size, ability to perform the method of probability proportional to size. The simulations show that the design can dominate its rival design in probability proportional to size sampling.
Sayed Mohammad Reza Alavi, Sara Nayyeri, Mohammad Reza Akhoond,
Volume 13, Issue 2 (2-2020)
Abstract
In many sample surveys, the variables of interest, such as student cheating in a university are sensitive in nature. In such situations, the interviewees respond to direct questions untruthful, or refuse to answer. The various indirect methods such as randomized response technique and item count technique are introduced to collect sensitive information. In this paper a new item count is proposed, then its randomized version called randomized item count model is introduced. Using this model an unbiased estimator for the sensitive proportion of the population is obtained. The variance of the estimator and an estimate for its variance are obtained. A criterion for comparing efficiency and privacy is introduced simultaneously. Using simulation, the proposed model is evaluated and its efficiency and privacy are compared with the Simons’ technique. Based on this criterion, it is shown that the proposed method is better than the Simons method. The proportion of student cheating in the Shahid Chamran University of Ahvaz is estimated using the proposed model.
Ali Najafi Majid Abadi, Nader Nematollahi,
Volume 14, Issue 2 (2-2021)
Abstract
Judgment post-stratification is a method of using additional information of ranking in the simple random sampling, to increase the efficiency of the estimators of population parameters. In this paper, we use judgment post-stratification instead of simple random sampling in stratums of stratified sampling, and present new estimators for population mean. Then, we compare the proposed estimators with random stratified mean estimator by using a simulation study. The simulation results show that the proposed estimators perform better than the random stratified mean estimator in most of the cases.
Hamed Salemian, Eisa Mahmoudi, Sayed Mohammad Reza Alavi,
Volume 18, Issue 1 (8-2024)
Abstract
Often, in sample surveys, respondents refused to answer some questions of a sensitive nature. Randomized response methods are designed not to reveal respondent confidentiality. In this article, a new quantitative randomized response method is introduced, and by conducting a series of simulation studies, we show that the proposed method is preferable to the cumulative and multiplicative methods. By using unbiased predictors, we estimate the covariance between two sensitive variables. In an experimental study using the proposed method, the average number of cheating and the average daily cigarette consumption of the Shahid Chamran University of Ahvaz students are estimated along with their variance, and an estimate for the covariance between them is provided.
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