Which of the following is true regarding probability samples?
a. They are as perfect as a census and contain no errors caused by competitors.
b. They will always contain some inaccuracy (sample error).
c. They contain serious mistakes, but can be adjusted by statistical weighting procedures.
d. They are particularly susceptible to nonsampling errors.
e. When they approach large values, say 1,000, they are equivalent to a census.
Answer: b. They will always contain some inaccuracy (sample error).