Table 2.

Mean% Difference (±1 Standard Error) and Paired t-Test of Estimated Standing Prevalence from Comparison of Less Frequent Sampling with Monthly Estimates of Estimated Standing Prevalence (Monthly, Mean, and Weighted Mean)

	Grid 11			Grid 12
	Monthly	Mean	Weighted mean	Monthly	Mean	Weighted mean
Bi-monthly
% difference	0.221	−0.021	0.098	0.872	1.036	1.033
SE	0.092	0.294	0.277	0.604	0.914	1.010
t1,84	2.413	0.073	0.355	1.435	1.127	1.017
P	0.018	0.942	0.724	0.155	0.263	0.312
Quarterly
% difference	1.048	1.233	1.394	0.371	1.050	0.893
SE	0.445	0.772	0.863	0.255	0.650	0.661
t1,56	2.355	1.597	1.615	1.440	1.601	1.340
p	0.022	0.116	0.112	0.155	0.115	0.186
Semiannually
% difference	0.652	0.752	0.683	0.742	2.303	2.335
SE	0.251	0.842	0.734	0.505	1.637	1.516
t1,26	2.555	0.879	0.913	1.443	1.382	1.514
p	0.016	0.387	0.369	0.160	0.178	0.141
Annually
% difference	0.965	2.602	2.887	1.494	5.439	5.319
SE	0.361	1.633	1.576	1.027	3.230	3.167
t1,12	2.579	1.535	1.765	1.402	1.622	1.618
p	0.023	0.149	0.101	0.184	0.129	0.130

Positive and negative values indicate that ESP was on average overestimated and underestimated, respectively. Significant differences are shown in bold. ESP, estimated standing prevalence; SE, standard error.