haphazard sampling

hap·haz·ard sam·pling

the assembly of data in an unprescribed and undefined fashion that allows no sound scientific inferences other than establishing the existence of types. (Finding even one unicorn in such a set would establish that unicorns can exist, but no inference about their prevalence could be made from it.) Compare: random sample.
References in periodicals archive ?
0 Opportunistic or haphazard sampling, including voluntary observer programs, to support bycatch or total catch estimation.
Because this study is an observational study with haphazard sampling, the precision and bias cannot be directly assessed.
The survey data were collected during the six-year survey under three different survey designs, none of which were strictly randomized, but each involved some degree of haphazard sampling due to weather, sediment structure, and other logistical restrictions for beam trawling in small bays off the Gulf of Alaska (Norcross et al.