## Steps and Confidence Intervals in Hypothesis Testing

This section lists four key steps in hypothesis testing and explains the close relationship between confidence intervals and significance tests.

### Significance Testing and Confidence Intervals

#### Answers

- You cannot reject the null hypothesis because the confidence interval shows that 20 is a plausible value of the population parameter.
- This study is testing the difference between means, and significant differences would be either larger or smaller than 0. Thus, confidence intervals that do not contain 0 represent statistically significant findings.
- The 99% confidence interval contains all of the values that the 95% confidence interval has, but it extends farther at both ends and has other values, too. If something is not significant at the .05 level, it is also non-significant at the .01 level.
- Because the
p value was .21, we know that the 95% confidence interval contains the null hypothesis parameter, .5. Thus, both of the confidence intervals that contain .5 are possible confidence intervals that this researcher could have computed.