At each centre, a random sample of inhabitants was drawn, yielding a sample of 10,567 institutionalised persons.
The sample was chosen by means of accidental (non-probability) sampling, yielding a sample size of n = 259 with an α risk = 0.05 for a precision of 5%.
The questionnaire response rate at infant birth was 74%, yielding a sample of 16,058 subjects (51.8% boys and 48.2% girls).
Of the remaining 2,935 children, 76.0% were enrolled in the study, yielding a sample size of 2,230.
In a new study, Kees-Jan Kan and colleagues analyzed the results of 23 independent twin studies conducted with representative samples, yielding a total sample of 7,852 people.
Of these, 3,949 completed the survey, yielding a survey completion rate of 55% (Callegaro and DiSogra 2008).
The mixed E. coli samples are then extracted, yielding a standard sample for analysis and optimization.
A total of 1018 participants completed the survey, yielding a final stage completion rate of 33%%.
One-hundred twenty (120) quit the survey after completing only a few initial questions, yielding a final sample of 510 trainees.
Sample sizes for the four sections were 42, 39, 36, and 42, yielding a combined sample size of 159.
