The second type of surveillance performance indicator is one which evaluates how well desired practices and procedures of a surveillance system are carried out to ensure that cases are investigated and appropriate laboratory specimens collected in a timely fashion. In our example concerning surveillance for cases of AFP and measles, the surveillance system is adequately adhering to recommended practices and procedures if at least 80% of cases reported to the surveillance system have: 1) case investigations initiated in a timely fashion; 2) appropriate laboratory specimens, when needed, collected for case confirmation; 3) specimens arrive at the proper diagnostic laboratory in good condition and in a timely fashion for testing; and 4) laboratory test results in identification of the source of infection. Performance indicators similar to these could be used to assess practices and procedures focused on surveillance of exposures to environmental and occupational toxicants, while those focused on chronic diseases could have laboratory components focused on proper and timely collection and identification of serum lipid, glucose, vitamin, and mineral levels.