Final answer:
A random sample is a subset of a larger population in which every member of the population has an equal chance of being selected.
Step-by-step explanation:
A random sample is a subset of a larger population in which every member of the population has an equal chance of being selected. Random samples are preferred because if the sample is large enough we can be reasonably sure that the participating individuals are representative of the larger population. This means that the percentages of characteristics in the sample-sex, ethnicity, socioeconomic level, and any other characteristics that might affect the results-are close to those percentages in the larger population.