Confidence intervals (based on the F-distribution and thestandard normal distribution) for the difference between two intraclass correlation coefficients under unequal family sizes based on two independent multinormal samples have been proposed. It has been found that the confidence interval based on the F-distribution produces better results than the confidence interval based on the standard normal distribution in terms of shorter average length. The coverage probability of the interval based on the F-distribution is competitive with that based on the standard normal distribution. An example with data is presented.

Z-test, F-distribution, intraclass correlation coefficient, confidence interval.