Table 4.

Observed (simulation) standard errors of estimates, and average bootstrap standard error estimates, along with coverage rates of nominal 95% and 90% confidence intervals for procedure given in Section 3.4 for varying sample proportion, homophily H, and activity ratio DA, and for various biases in the sample selection process. Observed standard errors are based on 200 samples. Bootstrap standard errors are the average bootstrap standard error estimates over the same 200 samples. Nominal confidence intervals are based on quantiles of the Gaussian distribution.

% sample	homoph. H	DA	sample bias	SE observed	SE bootstrap	coverage 95%	coverage 90%
5%	1	1	No	0.0200	0.0194	94.0%	86.1%
50%	1	2	No	0.0100	0.0103	95.4%	91.7%
5%	2	1	Initial	0.0321	0.0298	92.0%	85.5%
50%	2	2	Initial	0.0141	0.0162	98.1%	93.7%
5%	2	1	Referral	0.0388	0.0325	81.5%	69.0%