Chapter 15: Sampling

Chapter 15: Sampling

Complete Chapter Questions With Answers

Sample Questions Are Posted Below

MULTIPLE CHOICE

1. A researcher is studying sleep habits of household cats that belong to families with small children. The families live in urban areas. In this study, what are the elements?

ANS:  B

The individual units of the population and sample are called elements. The elements are the things the researcher studies. An element can be a person, event, behavior, or any other single unit of study. In this case, the researcher is studying cats—not children, not families, and not sleep.

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2. A researcher wants to increase the generalizability of a planned experimental study’s results. What can the researcher do, relative to sampling, that will achieve that goal?

ANS:  D

Random sampling increases the extent to which the sample is representative of the target population. Good representativeness enhances generalizability of the results. Selecting a sample larger than the size recommended by power analysis results only is a larger sample, not a more representative one. Purposive selection of a more heterogeneous sample does not increase the sample’s representativeness. Use of random assignment has no effect on representativeness of the sample, since it is selected before assignment occurs.

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3. A researcher studies spending habits of teenagers in strip malls. From what kind of population has the researcher selected her sample?

ANS:  A

An accessible population is the portion of the target population to which the researcher has reasonable access. The sample is obtained from the accessible population by a particular sampling method. The target population is the entire set of individuals or elements who meet the sampling criteria. The sample is selected from the accessible population within the target population, since this is the population from which the researcher can actually select subjects. The sample here is a subset of the accessible population that actually checks into shelters, not the target population of all homeless persons. The entire population is a particular group of people who share one or more characteristics that are the focus of the research.

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4. A researcher selects his sample in this way. He paints numbers on 100 ping-pong balls, and he paints half of them blue and half of them green. He puts the blue half onto a large tray, and the green half of them onto another large tray. Then he mixes each group and trains his dog to bring 10 balls from each tray to him, gently and systematically, one at a time. What type of sample is this?

ANS:  C

Stratified random sampling is used when the researcher knows some of the variables in the population that are critical to achieving representativeness. Variables commonly used for stratification are age, gender, ethnicity, socioeconomic status, diagnosis, geographical region, type of institution, type of care, care provider, and site of care. The dog has no agenda, and the balls are mixed. The dog chooses 10 balls from each stratum. The sample is stratified random.

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