Exam 11: Quantitative Methodology: Interventional Designs and Methods

A researcher is comparing a new and less expensive treatment with an established treatment, in hopes of showing that there is no difference in outcome. The researcher does not perform a power analysis and, consequently, selects a sample size that is smaller than what would be recommended for an analysis of variance. The results show that there is a significant difference in outcome between the two treatments, and that the new treatment has poorer outcomes. What is the negative result of the researcher's decision to use a smaller sample?

Threats to statistical conclusion validity include which of the following?

A posttest-only design with a comparison group, which is a quasi-experimental study, lacks conditions present in an experimental study. Which components are lacking in this type of study design?

Why does a researcher perform a post hoc analysis comparing characteristics in experimental group and control group?

Causality is tested through which of the following?

Which research methods test for causality?

A study's hypothesis that a new surgical approach produces safer outcomes in immunosuppressed patients is tested in a 14-site research study across the United States. Subjects at all sites are randomly selected and randomly assigned to experimental versus control groups. What strategy is used in this research project?

A researcher measures the dependent variable in an interventional group of subjects both before and after an intervention. The researcher also measures the same dependent variable in a non-interventional group, at the same two points in time. The groups are not randomly assigned. What kind of design is this?

A researcher states in an article, "The subjects acted as their own controls." If this is true, what does this imply?

A researcher tests a new intervention for nausea associated with chemotherapy in hospitalized patients. The researcher does not want to suggest nausea to the patients, so as the dependent variable, the researcher uses the answer the patients give to the question, "How are you feeling this morning?" This is a threat to which type of validity?

A researcher believes that therapy is more effective if patients exercise. The researcher tells the patients that it has been arranged for them to use the hospital gym, if they so desire-and that if they are interested, they will then be in the experimental group. This represents which threat to internal validity?

Aside from random assignment using a large sample, what are design strategies that control for known extraneous variables?

What is the strategy used to determine whether the carryover effect exists?

Patients in an outpatient treatment center receiving daily wound care were studied by means of an experimental design using a crossover strategy. Patients were administered either Morphine Contin or Percocet, by random assignment, on one day, and the other medication on the following day. Pain scores were obtained for both days, recorded and analyzed. Why was a crossover strategy used?

Immediately after the intervention in an experimental study of the negative effects of smoking tobacco, the state tax on cigarettes increases the cost from $4 to $8 per pack. Which threat to internal validity does this pose?

Nurses who provide discharge teaching to patients after colonoscopy call these patients the day after the procedure to check on their status. At that time, patients who have had polyps removed invariably ask how long it will be until they receive their results. The nurses decide to design a study in which they will change their discharge teaching, in order to include information about the time frame for biopsy results. The nurses then will measure patient satisfaction results, comparing them with the results for the previous month, before the change. Which type of research design will they use?

John Stuart Mill insisted that in order for causation to be demonstrated, there must be no alternative explanation for why a change in one variable leads to a change in the other variable. This concept of alternative explanations is the idea that underlies which type of validity?

A researcher tests a new intervention for nausea associated with chemotherapy, in hospitalized patients. At the same time, a new over-the-counter medication containing natural herbs is marketed aggressively, and some of the hospital patients are given this herbal remedy by their families. This is a threat to which type of validity?

In interventional research, why does subject attrition affect internal validity?

A researcher uses matching to constitute a control group, while performing a study on psychotherapy as an adjunct treatment for substance addiction. What type of validity might be enhanced by matching, in this instance?