Simpson Pharmaceutical Company

Q1: What is the recovery rate for the 400 patients assigned Zidek? What is the recovery rate for the 400 patients assigned the placebo? Which group ("Zidek" vs. "Placebo") had the higher recovery rate?

* Solution : Zidek : 204/400 = 0.51, Placebo : 164/236 = 0.41

* Answer : The recovery rate of Zidek is higher than that of Placebo.

Q2: For the male patients, what is the recovery rate for those assigned Zidek? What is the recovery rate for those assigned the placebo? Which group ("Zidek" vs. "Placebo") had the higher recovery rate?

* Solution : Zidek : 192/320 = 0.6, Placebo : 71/100 = 0.71

* Answer : The recovery rate of Placebo is higher than that of Zidek.

Q3: For the female patients, what is the recovery rate for those assigned Zidek? What is the recovery rate for those assigned the placebo? Which group ("Zidek" vs. "Placebo") had the higher recovery rate?

* Solution : Zidek : 12/80 = 0.15, Placebo : 93/300 = 0.31

* Answer : The recovery rate of Placebo is higher than that of Zidek.

Q4: Is Zidek superior to the placebo as the overall results indicate? Or is Zidek less effective than the placebo, as the single-gender results indicate? Why? Discuss how such seemingly anomalous results can occur. What is the one thing we can be sure about concerning gender and the disease?

Zidek Placebo

Recovery Not-Recovery Recovery Not-Recovery

Male 192 320 71 100

Female 12 80 93 300

Total 204 400 164 400

Q4-1) Is Zidek superior to the placebo as the overall results indicate?

* No. Because the medicine is prescribed to either male or female, not to both.

Q4-2) Is Zidek less effective than the placebo, as the single-gender results indicate? Why? Discuss how such seemingly anomalous results can occur.

* Mathematically, "a/b < c/d" & "a'/b' < b'/d'" does not mean "(a+a')/(b+b') < (c+c')/(d+d')".

* The reason for getting this kind of result is because the ratio of male and female is different in Zideck and Placebo. In order to achieve an accurate result, Zideck and Placebo must both have the same male/female ratio.

Q4-3) What is the one thing we can be sure about concerning gender and the disease?

* According