Question 1

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?

Accepted Answer

The scenario describes a situation where participants self-select into groups, which can introduce biases related to characteristics that influence their choice, thus threatening internal validity through selection bias.

Question 2

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

Accepted Answer

The answer of In interventional research, why does subject attrition...

Question 3

Causality is tested through which of the following?

Accepted Answer

Experimental research and quasi-experimental research are designed to test causality by manipulating variables and observing the effects on other variables.

Question 4

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?

Accepted Answer

The answer of A nurse notes that in clients with...

Question 5

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?

Accepted Answer

The answer of What are the differences between the simple...

Question 6

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?

Accepted Answer

The answer of In a national health study, begun in...

Question 7

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

Accepted Answer

The answer of What is the most effective way to...

Question 8

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?

Accepted Answer

A Type I error occurs when a study incorrectly rejects the null hypothesis, suggesting a treatment effect when there is none. The initial study showing significance, followed by three replication studies failing to show significance, suggests the first study may have falsely identified an effect, indicative of a Type I error.

Question 9

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?

Accepted Answer

The answer of Patients in an outpatient treatment center receiving...

Question 10

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?

Accepted Answer

Partitioning refers to dividing the data into more specific segments or categories to analyze relationships that might not be apparent when looking at the data as a whole. In this scenario, the researcher initially found no significant relationship between exercising at a gym and quality of life but later discovered a significant relationship when analyzing the data based on the frequency of gym visits. This indicates that by partitioning the data according to the number of times participants went to the gym, the researcher was able to uncover a significant relationship that was not visible in the aggregated data.

Question 11

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

Accepted Answer

An RCT must include random assignment to groups to ensure that each participant has an equal chance of being placed in any group, reducing bias. It also involves an interventional design where the researcher actively intervenes to test the effects of a treatment or intervention.

Question 12

Threats to statistical conclusion validity include which of the following?

Accepted Answer

Fishing, low statistical power, and violated assumptions of statistical tests are threats to statistical conclusion validity as they can lead to incorrect conclusions about the relationship between variables. Maturation and history are threats to internal validity, not statistical conclusion validity.

Question 13

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

Accepted Answer

The answer of Aside from random assignment using a large...

Question 14

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

Accepted Answer

The answer of Why does a researcher perform a post...

Question 15

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

Accepted Answer

Counterbalancing is used to control for carryover effects in repeated measures designs by varying the order in which treatments are administered across participants, ensuring that the order does not confound the results.

Question 16

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

Accepted Answer

The answer of What designs can a researcher use, so...

Question 17

Which research methods test for causality?

Accepted Answer

Experimental and quasi-experimental research designs are specifically structured to test for causality by manipulating one or more independent variables to determine their effect on dependent variables, with the key difference being the level of control and randomization.

Question 18

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?

Accepted Answer

The answer of A posttest-only design with a comparison group,...

Question 19

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

Accepted Answer

The answer of A researcher states in an article, "The...

Question 20

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

Accepted Answer

The answer of In which of the following ways does...

Quiz 11: Quantitative Methodology: Interventional Designs and Methods