A study was considered to be of a good quality if the sample size was determined by considering expected prevalence and desired precision of the estimate; animals were sampled by using a probability sampling method; bacterial isolation and identification were done by using steps that involved pre enrichment, selective enrichment and biochemical tests.
The KNHANES, a nationwide survey which obtains national-level health statistics, ensured that the samples were representatives of the population by selecting subjects using a probability sampling method [ 22].
These 3 population-based telephone surveys were conducted in selected sites located throughout the United States, including Georgia, by using a probability sample design.
A probability sample was obtained by approaching all the subjects in a consecutive manner.
However the study had a few limitations; it was constrained by a small sample size that was recruited by a non-probability sampling procedure from a dental clinic environment which reduces the generalizability of the study findings.
MMP is a national probability sample of patients in care for HIV infection, constructed by multi-stage probability sampling including a probability proportional to size (PPS) sample of states, a PPS sample of facilities within selected states, and an equal probability sample of patients within selected facilities [22].
The participants of the NHF study consisted of residents on the federal electoral rolls of December 1988 in North and South Sydney, Melbourne, Brisbane, Adelaide, Perth, Hobart, Darwin and Canberra in a systematic probability sampling by sex and 5-year age groups.
The instrument (OHQoL-UK©) developed by McGrath & Bedi used a random probability sampling method.
The data were collected at 119 Spanish mental health centers, selected by probability sampling adjusted by population weights from the 17 Spanish Autonomous Communities, with the participation of 132 psychiatrists duly trained in administering the instrument with a video designed for that purpose.
