Table 2.

Linear mixed effects model parameters for calibrating the GNBBP model to US county data.

Variable	Symbol
Fixed effect slope (Malthusian parameter)	$\alpha$
Fixed effect intercept	$\gamma$
County level slope random effect	$a_i$
County level intercept random effect	$g_i$
Slope random effect variance	${\sigma }_1^2$
Intercept random effect variance	${\sigma }_2^2$
Model variance	${\sigma }^2$