Exam 15: Sampling

Five hundred persons were chosen to participate in a study, 270 women and 230 men, representative of the proportion of adult women and men in the population of Portland, Oregon. Patients were selected using a table of random numbers, from a master list of all patients who had been treated for congestive heart failure (CHF) in the previous 3 months at one of Portland's four main hospitals. This is an example of what type of sampling strategy?

A researcher studies spending habits of teenagers in shopping malls. The researcher visits two local malls to solicit participants. From what kind of population has the researcher selected the sample?

Why is subject selection in survey research considered nonrandom?

A study has a power level of 0.75. What does that mean?

If all of the tickets purchased in this week's state lottery is considered the population, the five winning tickets drawn on Saturday constitute the sample. If the lottery is not "fixed," why is this a probability sample?

Large sample sizes are desirable in which types of research?

A researcher studying depression in relation to five predictor variables decides to include five more variables in a study because the literature reveals that they may also be involved in depression. Consequently, the researcher should do which of the following?

Choose the nonprobability sampling method.

Using a table of random numbers, a sample of 400 subjects was selected from the list of the license numbers of all registered nurses in the state of Michigan. Each nurse was sent a letter requesting completion of an online survey on workplace bullying. This is an example of what type of sampling method?

A researcher has already written a study proposal and performed a power analysis, which indicates that the sample size will have to be at least 36, in order to avoid Type II error. The researcher then decides to set the level of significance at p < 0.01 rather than p < 0.05 but wants to maintain power at 0.80. What will the researcher have to do in order to maintain sufficient power?

Why is a large refusal rate a barrier to widespread generalization?

How does effect size relate to instrument sensitivity?

"To be considered eligible for the study, subjects had to be older than 21 years of age, hold a valid state driver's license, and be able to fire a shotgun." What part of the study sample description is this?

Inclusion sampling criteria differ from sample characteristics. Which of the following are sample characteristics from a study conducted in a neurosurgical critical care unit of a major hospital?

A researcher consented 400 subjects, but 12 dropped out of the study before it was completed. The rest finished the study. What was the sample retention rate?

If researchers are attempting to recruit subjects who are members of a group that is not mainstream and may be disdained, why is snowball sampling often used?

A researcher attempted to recruit all 150 of the patients seen in the emergency department in a 3-month period for diverticulitis, but only 120 consented to participate. What is the refusal rate?

Choose the sampling design that is an example of a probability sampling method.

Why are convenience samples used so frequently in nursing research?

If the population is E, and assuming the researcher selects part of the population as a sample, what could be the sample?