  Linear mixed-effect models with two variance components are often used when
variability comes from two sources. In genetics applications, variation in
observed traits can be attributed to biological and environmental effects, and
the heritability coefficient is a fundamental quantity that measures the
proportion of total variability due to the biological effect. We propose a new
inferential model approach which yields exact prior-free probabilistic
inference on the heritability coefficient. In particular we construct exact
confidence intervals and demonstrate numerically our method's efficiency
compared to that of existing methods.
