In order to measure preferences among mall loyalty rewards members towards the five main or anchor department stores, Steven the stats intern was assigned to collect some data. He sorted the membership according to age, from teensto octogenarians, and then randomly selected 50 from mutually exclusive age category to respond to an e-mail question about the stores.

Which statistical sampling technique best describes his methodology?

1. cluster sampling
2. convenience sampling
3. judgment sampling
4. network sampling
5. quota sampling
6. simple random sample
7. snowball sampling
8. stratified sampling
9. systematic sampling