Posted by Charlene on .
will someone just double check my answers, please.
Identify which types of sampling is used:random,stratified, systematic,convenience.
1. a sample consists of every 20th student who leaves the bookstore.
answer:systematic
2. a pollster uses a computer to generate 500 random numbers, then interviews the voters corrosponding to those numbers.
Answer:stratified

Math 
DQR,
Number 2 doesn't look like stratified to me: there's no stratification involved. Stratification is the process of grouping members of the population into relatively homogeneous subgroups before sampling, whereas here the pollster is simply picking voters at random, with each voter presumably ("presumably" because we don't know anything about the random number generator he's using) having an equal chance of being picked. That's simple random sampling.