Colloquium Biometricum

Vol: 32 Page: 213

Authors:

Title:
Note on shortening the conficence intervals in normal populations by enlarging the sample

Language: English

Keywords:

normal distribution

confidence interval

sample size

Summary:
The problem of shortening the length of confidence intervals for expected value and for variance in normal distribution is considered. For the 100(1-α)% confidence interval of length l_n based on a sample of size n the question is: how many k additional observations should we take so that the probabilistic inequality P(l_n+k/l_n≤p)≥q was satisfied. In the paper the values of k for n=5,8(2)20,25(5)40,50(10)100; p=0.5(0.1)1; q=0.95, 0.9; α=0.1, 0.05, 0.01 are given.