The list of sampling units from which the sample is selected.

A study in which two randomly equivalent samples of students are selected.

A random sample of the county population was selected, and letters were sent to 1,724 people telling them they had been chosen.

These samples are scientifically selected to represent the larger group.

A sample of 1,260 children ages three to four were selected as the final sample.

A new and expanded 85-area sample was selected based on the 1970 Census of Population.

Disadvantageous, if a sample is not carefully selected, results may be biased.

The original samples of telephone exchanges were selected by a computer, making sure that each region was represented in proportion to its population.

A random sample of children in the surveyed households was selected for more in-depth questioning.

A random sample of 100 (75 male/25 female) was selected to test the new scoring key and the results correlated against the original trials.