Table 4.

Birth and death rates stratified by different concentrations of antibody, where $\lambda =e^{{\mathbf{z}}_i^{\prime }{\mathit{\theta }}_{\lambda }}$ and $\mu =e^{{\mathbf{z}}_i^{\prime }{\mathit{\theta }}_{\mu }}$. We obtained asymptotic standard errors by applying the delta method to the asymptotic variance matrix of our estimate of θ. Note that the birth rate λ decreases much more rapidly than death rate μ as antibody concentration increases.

Antibody Concentration	λ		μ
	Estimate	SE	Estimate	SE
0	4.357	0.703	3.333	0.711
0.025	4.345	0.696	3.333	0.705
0.25	4.243	0.643	3.331	0.66
2.5	3.754	0.478	3.325	0.488
10	3.276	0.494	3.319	0.505