The null hypothesis for a particular experiment is that the mean test score is 20. If the 99% confidence interval is (18, 24), can you reject the null hypothesis at the .01 level?
false
Yes
true
No
You cannot reject the null hypothesis because the confidence interval shows that 20 is a possible population parameter.
Select all that apply. Which of these 95% confidence intervals for the difference between means represents a significant difference at the .05 level?
true
(-4.6, -1.8)
false
(-0.2, 8.1)
false
(-5.1, 6.7)
true
(3.0, 10.9)
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.
If a 95% confidence interval contains 0, so will the 99% confidence interval.
true
True
false
False
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.
Select all that apply. A person is testing whether a coin that a magician uses is biased. After analyzing the results from his coin flipping, the p value ends up being .21, so he concludes that there is no evidence that the coin is biased. Based on this information, which of these is/are possible 95% confidence intervals on the population proportion of times heads comes up?
true
(.43, .55)
false
(.32, 46)
true
(.48, .64)
false
(.76, .98)
false
(.81, 1.33)
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.