Question

Question 3

Consider the following situation:

Suppose we are looking at a weight loss program. The study looks at the weight of participants at the beginning of the program and at the end of the program. They then look at the difference in the weights to determine if the weight loss program causes a statistically significant drop in weight, on average. Note: A positive weight difference means the participant lost weight. The results of the study are summarized below.

Mean difference in weight	6kg
Standard deviation of difference in weight	8 kg
Sample Size	15
p-value	0.20

The researcher concludes that, since the p-value is the probability that the null hypothesis is true, then the null hypothesis is not unlikely to be true. So there is not enough evidence to suggest that the weight loss program was effective.

There is something wrong in the above statement. What is wrong? Explain why it is wrong.

Answer 1

The researcher concludes that, since the p-value is the probability that the null hypothesis is true, then the null hypothesis is not unlikely to be true. So there is not enough evidence to suggest that the weight loss program was effective.

the p-value or probability value is the probability of obtaining test results at least as extreme as the results actually observed during the test, assuming that the null hypothesis is correct.

Hence p-value is not the probability that the null hypothesis is true.

Again since p value is not small enough, so the null hypothesis is not unlikely to be true.So there is not enough evidence to suggest that the weight loss program was effective.