The Confidence Interval of Variance by Adjusted Bonett-t with the Geometric Mean Method for Non-normal Distributions

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Anurak Tongkaw

Abstract

The objectives of this research were 1) to develop a confidence interval for the one-population variance for non-normal distribution data and 2) to study the efficiency of the confidence interval developed for non-normal distribution data. The simulation was implemented by using 50,000 Monte Carlo random samples of a given sample size from various non-normal distributions (Chi-square, Exponential, Gamma, and Weibull). There were 3 methods for estimating the confidence interval of variance for the one-population variance of non-normal distribution data: 1) Bonet's method, 2) The adjusted Bonett-t with the Median method, and 3) The adjusting Bonett-t with the geometric mean method. The performance considerations of the confidence interval consisted of coverage probability and average length. The results showed that when the sample size was small and the data were not normally distributed, the adjusted Bonett-t with the geometric mean method performed better than the other methods.

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Applied Science Research Articles

References

S. Pongwichai, Statistical data analysis by computer: emphasizing for research, 26th ed. Bangkok: Chulalongkorn University Press, 2015. (in Thai)

K. Vanichbuncha, Principles of Statistics, 12th ed. Bangkok: Chulalongkorn University Press, 2010 (in Thai). Figure 5 Histogram diagram of satisfaction data.

D. G. Bonett, “Approximate confidence interval for standard deviation of nonnormal distributions,” Computational Statistics & Data Analysis, vol. 50, no. 3, pp. 775–782, 2006.

S. A. Niwitpong and P. Kirdwichai, “Adjusted Bonett confidence interval for Standard deviation of non-normal distributions,” Thailand Statistician, vol. 6, no. 1, pp. 1–16, 2008.

W. Pan, “Approximate confidence intervals for one proportion and difference of two proportions,” Computational statistics & data analysis, vol. 40, no. 1, pp. 143–157, 2002.

U. Olsson, “Confidence intervals for the mean of a log-normal distribution,” Journal of Statistics Education, vol. 13, no. 1, pp.1–9, 2005.

A. Sakworawich, Descriptive Statistics, Exploratory Data Analysis, and Statistical Graphic with Basic R Programming, 2th ed. Bangkok: Chulalongkorn University Press, 2017 (in Thai).

A. Tongkaw, “Confidence intervals for a ratio of two population medians by price and bonett bootstrap-t method,” The Journal of KMUTNB, vol. 32, no. 2, pp. 457–468, 2022(in Thai).

B. Phuenaree, & S. Sanorsap, “An Interval Estimation of Pearson’s Correlation Coefficient by Bootstrap Methods,” Asian Journal of Applied Sciences, vol. 5, no. 3, pp. 623–627, 2017.