Exam 11: Quantitative Methodology: Interventional Designs and Methods

A nurse notes that in clients with multiple tattoos, many are missing quite a few of their teeth. The nurse measures the variables and establishes a negative correlation between number of tattoos and number of teeth. The nurse designs a study to measure causation. Why is this problematic?

In a national health study, begun in 2012, thousands of nurses have been participating in ongoing research to better understand the effects of omega-3 fish oil and vitamin D-3 upon cardiovascular health and bone health. Subjects are randomly assigned to experimental or control group, for the two variables. Data about cardiovascular health and bone health will continue to be collected over many years. This study could be an example of what types of research?

A researcher tests the effect of a new laparoscopic treatment for chronic shoulder dislocation, comparing it with an older treatment. The results are statistically significant, and the researcher states in the study findings that there is evidence that the treatment has promise for widespread application. A subsequent replication study fails to show statistical significance. A third and fourth study produce the same effects as the second. Sample sizes are determined to be sufficient in all four studies. What is the most likely explanation here?

What is the most effective way to minimize the effect of a large number of unknown extraneous variables?

The researcher divides his lab rats into two groups and administers IV methamphetamine to one of the groups, in order to determine its effect on the fear-flight response. This is an example of which of the following?

What designs can a researcher use, so as to control for the testing threat?

A researcher conducts a study examining the relationship between exercising at a gym and quality of life in elders over 70 years of age. There appears to be no statistically significant relationship. Then the researcher analyzes the data again, this time comparing number of times a week the participant goes to the gym and quality of life and finds that there is a statistically significant relationship. This is an example of which of the following?

A group of 25 Labrador retrievers, and their owners, are brought to the research lab, one at a time. The Labrador retrievers are shown various stimuli, including a squirrel that runs along a wire at the top of the lab, to elicit barking. Then the owners command the dogs to stop barking, and the stimulus is repeated. The duration of barking is measured. Then the owners are taught a different technique for quieting their barking dogs. A week later, the dogs and their owners return to the lab, the stimuli are introduced, and the duration of barking is measured. This is an example of what type of design?

A researcher is designing a randomized-controlled trial (RCT). What must an RCT contain?

In which of the following ways does the researcher control for threats to construct validity?

Identify the study design used in the following research project: Twenty patients, all of whom have bipolar mania, have been placed on lithium and also begun on a medication believed to prevent rapid cycling. The patients are followed for 12 months, at which time they are seen by a psychiatrist monthly, to adjust their dosages. Medication compliance, emergency department visits, and mental health hospitalizations are measured. These are compared with another group of patients with the same mental illness, being treated on lithium alone. What is this design?

A researcher conducts interventional research and uses a small sample that is not randomly selected. When the researcher replicates the study, twice, the researcher again uses the same site and another small sample that is not randomly selected. This is a threat to which type of validity?

What is the essential difference between a control group and a comparison group?

A study using the factorial design measures the effect upon hemoglobin levels of four independent variables, each administered randomly and independently. How many distinct groups are there in this factorial design?

Subjects in a multiple group experimental study are tested for how much time it takes them to navigate a maze and find the chocolate. The maze is reconstructed after each run, and three different floor plans are used. Each group is tested eight times in 8 hours at a different time of day. The runs later in the day have faster times than the earlier ones. Which threat to internal validity might account for this difference?

If a one-group pretest-posttest study uses subjects as their own controls, which is the study design?

Hospital nurses are observed in order to determine exactly how long they swab IV ports with alcohol. Because they are being observed, they "scrub the hub" longer than they ordinarily would have. This is an example of what concept relevant to quantitative research?

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 no significant difference in outcome between the two treatments. Which type of validity is affected by this?

The essentialists insisted that a cause be necessary and sufficient for an effect to occur. In a modern study, alcohol dependency is found to lead eventually to permanent liver damage, except when the person with alcoholism consumes a diet plentiful in the B- vitamins. In addition, liver damage can emerge in the absence of alcohol dependency. What would the essentialists say about the causative relationship between alcohol dependency and liver damage?

What are the differences between the simple quasi-experimental pretest-posttest design and an experimental version of the same design with a control group, in which there is random assignment to group?