Which of the following conditions must be met for a scientifically valid
sample? subjects are selected: check all that apply.

a. at random.
b. from the most conveniently available people.
c. based only on who volunteers.
d. to represent the population.

The correct choices are:

A. At random

D. Represent the population

Explanation:

Random sampling ensures that every member of the population or group has an equal chance of representation. Random sampling eliminates the possibility of response or sample bias which gives a universal sample that uniformly represents all members of the population.A good sample should represent the entire population. This can be achieved by through random sampling.Convenience and volunteer based samples both have an increased risk of response bias. These samples will only represent selected individuals instead of the entire population.