Answer to Question 1
In a probability sample, each member of the target population has a known, nonzero
chance of being included in the sample. The chances of each member of the target
population being included in the sample may not be equal, but everyone has a known
probability of inclusion. With nonprobability samples, on the other hand, there is no
way of estimating the probability that any population element will be included in the
sample. Thus, there is no way of ensuring that the sample is representative of the
target population. All nonprobability samples rely on personal judgment at some point
in the sample-selection process.
Answer to Question 2
A