What is the difference between a probability sample and a nonprobability sample?
Probability Sampling:
A subset of the population that can be assumed to be a representative cross section of the population because every element in the population has a known non-zero chance of being selected.
Randomization techniques used to draw sample
Allows measurement of random sampling error
Nonprobability Sampling:
A subset of the population in which the chances of selection for the various elements in the population are not precisely known.
No randomization
Sampling error cannot be measured