Read the study and then answer the questions that follow
Below is a fictitious study.
Read the study and then answer the questions that follow, providing detailed explanations within your answers so that it is clear why you answered as you did. Each question is worth 1 point.
Bramble and Rumbledon are internal medicine physicians working in a hospital-affiliated clinic. They wish to study whether dietary changes with or without exercise, or exercise alone, will best improve their patient’s blood pressure (BP) readings. Many patients that come to their office are hypertensive and take BP medication daily. In order to recruit participants for their study, the physicians invited all adult patients presenting with hypertension, (without other medical problems), that called or visited their clinic for BP medication refills during the months of October and November 2018 to participate in the study.
All patients invited to participate in the study received written and oral information about the study participation requirements verbally and orally. Participants were of adult age, (18 years or older), spoke English, and were able to commute to the clinic when needed. Participants were to continue taking their regularly scheduled BP medications. Invited participants were told that the purpose of the study was to study measures to help decrease BP. Each participant was randomly assigned to a study group, and received further specific instructions for their group as outlined below. Participants were informed that they could withdraw from the study at any time, that all information would be kept confidential, and study results would be shared only in anonymous, aggregate fashion. Participants were encouraged to call or visit the clinic with questions at any time during the study. The Internal Review Board of the hospital affiliated with the clinic reviewed and approved the study.
A total of 150 patients were invited to participate in the study; 90 agreed and signed the consent form. Thirty participants were assigned to study group A; these participants received specific, detailed information and instruction to eat a meat and dairy free diet, consisting primarily of whole grains, fruits and vegetables for 8 weeks, to exercise a minimum of 30 minutes 4x/week, and continue their prescribed BP medications.
Thirty participants where assigned to study group B, and received specific information and instructions to exercise for a minimum of 30 minutes 4x/week, and continue their prescribed BP medications. Participants were to eat their usual diet.
Lastly, thirty participants were assigned to Group C, a control group, where the instructions were to continue to take their prescribed BP medications. Participants were to eat their usual diet and exercise per whatever their usual routine was.
All participants in all groups were instructed to come to the clinic every 2 weeks for a BP reading. These appointments were scheduled before the study began. All participants had past BP records available which were used to compare individual participant changes in BP measurements during and after the intervention period (i.e. pre and post test data).
During the study, 14 patients in the diet and exercise group (Group A) dropped out of the study. Ten patients in the exercise only group (Group B) also dropped out of the study., and ten patients in the control group (Group C) dropped out of the study. The remaining patients all reported following the instructions for their assigned group, and came to the clinic for BP readings as scheduled every 2 weeks, thus completing the study.
Patients lived at home during the study. The participants in Group A were responsible to make their own meat and dairy free meals, and keep a journal recording their dietary intake each day, their exercise sessions, and self-administration of their prescribed BP medications. The participants in Group B kept a journal recording their exercise sessions and self-administration of their prescribed BP medications. Group C kept a journal noting administration of their prescribed BP medications.
At the end of the study, all participants in Group A, (the diet and exercise group), had statistically significant reductions in their BP when comparing pre and post data readings. In Group B, ten of the participants had statistically significant reductions in their BP from pre and post data readings, while ten participants did not show any significant change between pre and post data readings. In Group C, three patients had a statistically significant reduction in their pre and post BP data readings, while four patients had statistically significant increases in their BP pre and post data readings. The remaining patients in Group C had no significant changes in BP pre and post data readings. The physician researchers concluded that exercise played an important part in helping decrease hypertension. They further concluded that eating a meat and dairy-free diet, primarily made up of whole grains, fruits and vegetables plus exercising regularly played an even greater part in reducing BP readings.
1. Please identify the independent and dependent variables in this study. Be sure to label them clearly.
2. Was this study experimental, quasi-experimental or non-experimental? After you have determined the type of study, also describe the specific design that was used for the type of study you selected? Explain your answers (see your text pp172-185) to help fully answer this question.
3. Was the study approach with patients ethical? Why or why not? (review what you learned in Chapter 2 about the ethics of conducting research, and use the index of your text to find information elsewhere in the text about the ethics of conducting research, as needed, to answer this question).
4. This question has two parts:
a. What is selection bias? When you answer this question, include the page #’s from your text that you used to answer this question.
b. Was selection bias a threat to internal validity in this study? Why or why not?
5. This question has two parts:
a. What is a history threat? When you answer this question, include the page #’s from your text that you used to answer this question.
b. Was history a threat to the internal validity of this study? Why or why not?
6. This question has two parts:
a. What does it mean when mortality occurs during the course of a study? In answering this question, include the page #’s from your text used in answering this question.
b. Did mortality occur during the course of this study, and if so, was it a threat to the internal validity of the study? Why or why not? Explain your answer.
7. Use your text to describe both causality and multi-causality. In answering this question, include the page #’s from your text you used in answering this question.
8. Now describe at least two ways in which this study met good criteria for establishing causality, and 2 ways that it failed to establish good criteria for causality.
9. Review the five major threats to external validity in your text on pp. 158-160. Then answer the following question: Do you think the results of this study can or should be generalized to other populations? why or why not – discuss at least two reasons to support your answer.
10. If you were going to replicate this study, what changes would you make to the design to make it more powerful? Indicate what type of study design you would recommend, and then identify a minimum of four things that you would change or do differently as a result.
Image preview for read the study and then answer the questions that follow