A pharmaceuticals company claims to have developed a cure for the common cold. In order to test whether this is true, one group of recent cold-sufferers was given this medicine and another group was given a placebo instead. The selection process was completely random.
The participants were examined two hours after they were given the medicine or placebo.
The results are tabulated below:
Placebo Medicine Total
No Effect 37 40 77
Cold Cured 22 23 45
Total 59 63 122
You plan to test whether the medicine has any effect on the cold by conducting a chi-square test for association on the data available.
Calculate the chi-square test statistic (X^2) using SPSS. Give your answer to 4 decimal places.
a) X^2 =
b) At alpha = 0.05, the null hypothesis that the medicine has no effect is rejected or not rejected.