Final answer:
Christopher uses systematic sampling by selecting every 10th band member to study their sleeping habits. This method involves choosing a random starting point and then selecting every nth member from a list.
Step-by-step explanation:
To study the sleeping habits of all band members in his school, Christopher obtains a list of the band members and collects data from every 10th person on the list. This type of sampling is known as systematic sampling. In systematic sampling, a sample is drawn by selecting a starting point at random and then picking every nth element in successions from the list. It is different from other types such as stratified sampling, where the population is divided into strata and samples are taken from each stratum; cluster sampling, where the entire population is divided into clusters, and random clusters are chosen; and convenience sampling, where samples are chosen based on convenience rather than a systematic approach.