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Precision of Genetic Variance and Heritability Estimates from Sorghum Populations 1
Author(s) -
Knapp S. J.,
Ross W. M.,
Stroup W. W.
Publication year - 1987
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1987.0011183x002700020029x
Subject(s) - heritability , confidence interval , statistics , variance components , point estimation , mathematics , biology , estimation , sorghum , population , zoology , demography , genetics , agronomy , management , sociology , economics
The emphasis of variance component and heritability estimation experiments has been on point estimation. Minimal attention has been given to confidence interval estimation. Our research was motivated by the limited use of confidence intervals and the importance of interval estimation to the statistical inference process. Our objectives were to evaluate variance component and heritability estimate precision from confidence interval estimate data and to describe the effects of experiment size and point estimate magnitude on interval estimate width. Point and interval estimates (1 ‐ α = 0.90) for the family variance component and heritability on a family mean basis were obtained from half‐sib, full‐sib, or S 1 family selection experiments in four sorghum [ Sorghum bicolor (L.) Moench.] populations. Agronomic traits were measured on 200 families per population grown on a Typic Argiudoll soil at Mead, NE, in 1981 and 1982 in a replications‐in‐incomplete blocks experimental design. Confidence interval estimate widths (widths) were functions of F =(family mean square)/(family ✕ year mean square) M f / M fy and tabled F ‐values determined by degrees of freedom for M f (df f ) and M fy (df fy ) and the confidence coefficient (1 ‐ α). Ratios of widths point estimates (ratios) decreased at a decreasing rate as F increased for fixed F ‐values. Widths and ratios decreased at a decreasing rate as df f and df fy increased for fixed F . Ratios for dr f = d fy = 190 for variance components were 0.32 for F = 10.0 and 4.27 for F = 1.11, and for heritability were 0.05 for F = 10.0 and 4.05 for F = 1.11. Our data demonstrated the problems of wide interval estimates for large experiments and variation in precision among point estimates for experiments of fixed size.