This outcome is typical of broad questionnaire surveys, with increased survey response rates in geographically-dispersed rural communities requiring significantly more resources.
In general, the matrix method provided moderate improvement in precision with increased surveying effort above thirteen kilometers while the marked recount method improved little if at all.
The effectiveness of mailed reminders has been demonstrated for head and neck cancer patients [ 13], with reminders at two and four weeks increasing survey response rates by 22%and15%5% respectively to achieve an overall response rate of 79.6%.
Population estimates for the DS method remained unbiased as the proportion of units intensively surveyed changed, but the variance of the estimates decreased with increasing proportion intensively surveyed.
The accuracy and precision of population estimates using both methods increased with increasing numbers of surveys and transects, though this increase was not linear (Figs. 2, 3, 4).
Spatial congruence between "true" and "estimated" hotspots declined rapidly with increasing time interval between surveys, due primarily to increasing false negatives (i.e., missing "true" hotspots).
Spatial accuracy decay with increasing time interval between surveys was higher for smaller-bodied (amphibians, reptiles, small birds, small mammals) than for larger-bodied species (birds of prey, hedgehogs, lagomorphs, carnivores).
Further, the increase-rates of A. petiolata-cover decreased with time since invasion, and concomitantly the cover of native woody species increased with increasing rates during the surveyed chrono-sequence (Lankau et al. 2009).
Among the exposed and unexposed retirees, the prevalence of LBP tended towards equivalence with increasing age in this national survey.
