incomplete ascertainment

in·com·plete as·cer·tain·ment

method of locating affected people in which probability of locating any specific patient has a known value between 0 and 1.
References in periodicals archive ?
In particular, the rates may be higher because of oversampling of persons of lower socioeconomic status during NHANES I, or they may be lower because of incomplete ascertainment of hospital stays or because persons diagnosed with but not hospitalized for CHD were not included (e.