Showing papers on "Intraclass correlation published in 1974"

Intraclass Reliability Estimates: Testing Structural Assumptions

Abstract: Intraclass correlation reliablity estimates are based on the assumption that the various measures are equivalent. Joreskog's (1970) general model for the analysis of covariance structures can be used to test the validity of this assumption.

Heritability and genetic correlation: statistical power, population comparisons, and sample size.

Abstract: The question of statistical power as it relates to estimates of heritability and genetic correlation, particularly with reference to population comparisons, is briefly discussed. Power tables (α=0.05) are presented for estimates of heritability and genetic correlation for four research designs (the regression of offspring on mid-parent values, the regression of offspring on single-parent values, the intraclass correlation of full sibs; and the intraclass correlation of half sibs) as a function of sample size. In addition, tables of statistical power for the comparison of heritabilities obtained from two different populations, using these four methodologies, are presented. These tables indicate that, for the study of a single population, 400 families of four members each is a sufficient sample to achieve a statistical power in excess of 95% for a heritability estimate of 0.20. However, in the comparison of heritabilities from two populations, 800 families of four members each, measured in each population, would be required to achieve equivalent statistical power for a difference in heritability of 0.20.

On inference about the mean in the presence of correlation

Abstract: The problem considered in this paper is that of developing a mode of inference about the population mean from a sample (from a normal distribution) which are correlated, using structural methods of statistical inference. The result for the general correlation model has been applied to the intraclass correlation model and the first order auto-regressive model.