Table 2.

Within-family variance (${\mathbf{\sigma }}_{\mathit{w}}^{\mathbf{2}}$) and number of records per family ( m ) for three group compositions

	$${\mathbf{\sigma }}_{\mathit{w}}^{\mathbf{2}}$$	m
One family	$$\frac{1}{\mathit{n}}\left({\mathrm{\sigma }}_{{\mathit{P}}_{\mathrm{D}}}^2+2\left(\mathit{n}-1\right){\mathrm{\sigma }}_{{\mathit{P}}_{\mathrm{DI}}}+{\left(\mathit{n}-1\right)}^2{\mathrm{\sigma }}_{{\mathit{P}}_{\mathrm{I}}}^2+\left(\mathit{n}-1\right)\mathit{r}{\mathrm{\sigma }}_{{\mathit{A}}_{\mathrm{T}}}^2\right)-\mathit{r}{\mathrm{\sigma }}_{{\mathit{A}}_{\mathrm{T}}}^2$$	o/n
Two families	$$\frac{4}{\mathit{n}}\left({\mathrm{\sigma }}_{{\mathit{P}}_{\mathrm{D}}}^2+2\left(\mathit{n}-1\right){\mathrm{\sigma }}_{{\mathit{P}}_{\mathrm{DI}}}+{\left(\mathit{n}-1\right)}^2{\mathrm{\sigma }}_{{\mathit{P}}_{\mathrm{I}}}^2+\left(\frac{\mathit{n}}{2}-1\right)\mathit{r}{\mathrm{\sigma }}_{{\mathit{A}}_{\mathrm{T}}}^2\right)-\mathit{r}{\mathrm{\sigma }}_{{\mathit{A}}_{\mathrm{T}}}^2$$	2o/n
n families	$$\mathit{n}\left({\mathrm{\sigma }}_{{\mathit{P}}_{\mathrm{D}}}^2+2\left(\mathit{n}-1\right){\mathrm{\sigma }}_{{\mathit{P}}_{\mathrm{DI}}}+{\left(\mathit{n}-1\right)}^2{\mathrm{\sigma }}_{{\mathit{P}}_{\mathrm{I}}}^2\right)-\mathit{r}{\mathrm{\sigma }}_{{\mathit{A}}_{\mathrm{T}}}^2$$	o

r, N, n, o and ${\mathrm{\sigma }}_{\mathit{b}}^2$ do not differ between group compositions.