The Number of Classes data set posted in our StatCrunch Grou

The “Number of Classes” data set posted in our StatCrunch Group provides the number of classes a group of randomly selected STAT 250 students are taking this semester.

a)      Using the variable named “Number of Classes”, create a dotplot of this information. Describe the distribution in context of the data set.

b)      Calculate the percentage of students taking either 4 or 5 classes this semester?

Problem 3: Data Collection and Experimentation. (14 Points)

A doctor who believes strongly that antidepressants work better than “talk therapy” tests depressed patients by treating half of them with anti-depressants and the other half with talk therapy. After six months, the patients are evaluated on a scale of 1 to 5, with 5 indicating the greatest improvement; write your answers in complete sentences.

a)      The doctor is concerned that if his most severely depressed patients do not receive the antidepressants, they will get much worse. He therefore decides that the most severe patients will be assigned to receive the antidepressants. Explain why this will affect his ability to determine which approach works best.

b)      What advice would you give the doctor to improve his study?

c)      The doctor asks you whether it is acceptable for him to know which treatment each patient receives and to evaluate them himself at the end of the study to rate their improvement. Explain why this practice will affect his ability to determine which approach works best.

d)      What improvements to the plan in part (c) would you recommend?

Solution

a) The doctors ability to choose the best method is affected due to the bias that he has towards anti-depressants. The ability to conclusively state whether the talk therapy worked or not would be affected if the most severe cases received anti-depressants.

b) To improve his study, the doctor must randomly assign people to both the groups. Also, to avoid any potential unfortunate event, the doctor may exclude the most highest level of patients from the study.

c) The above said procedure will again lead to a bias in the doctors head which might result it in him giving higher scores to the anti-depressant group as opposed to talk-therapy group.

d) The improvement on the plan would be to assign a score without knowing the treatment that the patient is getting and then check which method worked better.

Hope this helps.