Question

Beta endorphin are morphine like substances produced by the body. They create a sense of well-being. It has been proposed that Beta endorphin increase with exercise. Sport scientists conducted an experiment to investigate this problem. They used R to perform a hypothesis test and adopted a significance level of 0.05. The differences (dif) were computed as follows:

dif = Beta-endorphin post-test minus Beta-endorphin pre-test

The following R output was generated. Look at the R output generated. Answer each question below assuming the assumptions associated with this procedure are valid.

##

## One Sample t-test

##

## data: z$dif

## t = 6.8419, df = 8, p-value = 6.604e-05

## alternative hypothesis: true mean is greater than 0

## 95 percent confidence interval:

## 11.51382     Inf

## sample estimates:

## mean of x

## 15.81111

1. How many athletes took part in both the pre- and post-measurements?

2. Explain how the number 15.81111 was computed.

3. Formulate a null and alternate hypothesis in symbols and words.

4. What is the value of the test statistic?

5. Draw a picture that shows the test-statistic and critical t-value(s).

6. State the conclusions of the test for an expert and non-expert audience.

Answer 1