3-23. In a paper published in the journal Epidemiology, Dr. James E. Enstrom and

Question

3-23. In a paper published in the journal Epidemiology, Dr. James E. Enstrom and colleagues at UCLA recently reported on a study they conducted to assess the effects of taking multi- vitamin supplements containing vitamin C. In their study, the authors reviewed health data from a national sample of 11,348 people questioned in 1971-74 and followed up in 1984 to see if they were still alive. The study purported to show significantly lower death rates in men, and slightly lower death rates in women, among the group who took multi-vitamin pills containing vitamin C compared with those who didn't. a. Was this study a controlled experiment? Why? If not a controlled experiment, what kind of study was it? Be as specific as possible b. What is the response variable here? What are the factors? c. Is it valid to conclude that taking vitamin C causes lower death rates? Why or why not? d. What alternative explanation can you offer for the observed association between taking multi-vitamins with vitamin C and lower death rates?

Explanation / Answer

Ans A)- this study is a contolled experiment beacuse observer tested a hypothesis of inflence on the death rates by looking for changes brought on by effect of taking vitamin c in multi vitamin pills. since independent variable , vitamin c in the pills is the only factor that is allowed to be adjusted, keeping everything else same.  

Ans B)- response variable is the death rate.

Factors are

1. independent variable which is being altered that is vitamin c

2. dependent variable which is being measured that is death rate

C). It is not valid. beacuse-

To get better results, This experiment needs to be a Randomized trial. More random a trial is, the better result it will give. Three essential elements of a randomzed clinical trial is-

1. treatment must be imposed on the subjects of the study which is done in this example.

2. treatments imposed must be ramndomly assigned to eliminate other confounding variables. It will also increase the liklehood that the treatments groups are representative of the population.

3. replication- to independently confirm the results.

D) The association beween the vitamin c and lower death rates can be due to various other factors like diet of the person , age , other diseases. To confirm the association the test needs to be truly randomized.

  

Related Questions

Navigate

• Browse (All)
• Browse 3
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.