The Estimation For Location And Scale Parameters Of Logistic Distribution Under Median Ranked Set Sampling

In this paper, we study the estimations of location parameter θ and scale pa-rameter λ of the logistic distribution under ranked-set sampling. Using the method of two-factor theory, firstly we study the estimation of θ under A is known, by the method of the optimal allocation of the location parameter of symmetric distribu-tion which was proposed by Amarjot Kaur (2000), we determine a good ranked set sampling form and give a good unbiased estimation for the location parameter θ of logistic distribution. Then we substitute this good estimation for the unknown θ, and under this sampling method to obtain the maximum likelihood estimation of the scale parameter λ. Finally in the sense of mean square error (MSE),we compare this maximum likelihood estimation of the scale parameter λ with the maximum likelihood estimation of the scale parameter λ under simple random sampling (SRS) and balanced ranked-set sampling (RSS) respectively, we can get that this good sampling method is better than simple random sampling (SRS), and in some cases it also better than the balanced ranked-set sampling(RSS).