Comparing the means and variances of a bivariate log-normal distribution. 2008

Ionut Bebu, and Thomas Mathew
Department of Biostatistics, Bioinformatics, and Biomathematics, Georgetown University, Washington, DC 20057, USA.

For a bivariate log-normal distribution, a confidence interval is developed for the ratio of the means. The generalized confidence interval approach is used for this purpose, and the procedure is applicable regardless of the sample size. It is also noted that the same approach can be used to obtain a confidence interval for the ratio of the variances. A modified signed log-likelihood ratio procedure is also described for computing confidence intervals. The coverage probabilities of the proposed confidence intervals are estimated by Monte Carlo, and the generalized confidence intervals are found to exhibit satisfactory performance even for small sample sizes. Numerical results also show that the corresponding test procedures provide larger power compared with the modified signed log-likelihood ratio test. Two examples are given: one dealing with the comparison of the means and variances of health-care costs and the other dealing with testing mean equivalence in quantitative assays.

UI MeSH Term Description Entries
D016001 Confidence Intervals A range of values for a variable of interest, e.g., a rate, constructed so that this range has a specified probability of including the true value of the variable. Confidence Interval,Interval, Confidence,Intervals, Confidence
D016013 Likelihood Functions Functions constructed from a statistical model and a set of observed data which give the probability of that data for various values of the unknown model parameters. Those parameter values that maximize the probability are the maximum likelihood estimates of the parameters. Likelihood Ratio Test,Maximum Likelihood Estimates,Estimate, Maximum Likelihood,Estimates, Maximum Likelihood,Function, Likelihood,Functions, Likelihood,Likelihood Function,Maximum Likelihood Estimate,Test, Likelihood Ratio
D016014 Linear Models Statistical models in which the value of a parameter for a given value of a factor is assumed to be equal to a + bx, where a and b are constants. The models predict a linear regression. Linear Regression,Log-Linear Models,Models, Linear,Linear Model,Linear Regressions,Log Linear Models,Log-Linear Model,Model, Linear,Model, Log-Linear,Models, Log-Linear,Regression, Linear,Regressions, Linear

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