USGS PWRC web-site link USGS web-site link

Regional Credibility Measures

Although the BBS provides a huge amount of information about regional population change for many species, there are a variety of possible problems with estimates of population change from BBS data. Small sample sizes, low relative abundances on survey routes, imprecise trends, and missing data all can compromise BBS results. In the complicated model fitting procedures presently used for the BBS, it is possible that convergence failures in regions with these deficiencies can produce results that are inaccurate as well as imprecise. Often, users do not take these problems into account when viewing BBS results, and use the results inappropriately.

To provide some guidance to interpretation of BBS data, we have implemented a series of checks for some attributes that we view as cause for caution in interpretation of BBS results. We categorize BBS data in 3 credibility categories:

This category reflects data with an important deficiency. In particular:

This category reflects data with a deficiency. In particular: This category reflects data with at least 14 samples in the long term, of moderate precision, and of moderate abundance on routes.