True or False: 1. If higher levels of one variable are associated with higher le

Question

True or False:

1. If higher levels of one variable are associated with higher levels of another variable, then these variables are said to be positively correlated.

2. McNemar’s test is used for paired data in 2x2 contingency tables

3. If a p-value =.95, we can be 95% confident there is no difference between the groups.

4. Permutation tests are good for testing differences between groups when you don’t want to make assumptions about the shape of the distributions.

5. The standard error measures the variability in the individual data, while the standard deviation estimates the variability in the sample mean or treatment estimate.

6. A chi-square test is only appropriate if the expected counts in each cell of a table are greater than 5.

7. An outlier can cause more problems in a t-test than in a rank test.

8. If the null hypothesis is true, and you do a statistical test and get a p-value that is smaller than your alpha-level, you will reject the null hypothesis and make a type-2 error.

9. The width of a confidence interval increases as the sample size increases.

10. if a screening test has 90% sensitivity and 80% specificity, then 90% of people with disease will test positive.

11. If the sensitivity of a screening test is 95% and the disease is very rare, then the probability you have disease given that you got a positive test will also be close to 95%.

12. A confidence interval for a single mean gives a range of plausible values for that mean, while a population prediction interval gives a range of plausible values for a randomly chosen individual from the population.

13. If a 95% confidence interval for a difference in mean blood pressure between treatment and placebo groups is (.68, 1.3) then a 2-tailed test at =.05 would reject the null hypothesis that the groups are the same.

14. A correlation of 1 means the values for the two variables are exactly the same.

15. If you are comparing two groups with respect to 20 different variables, and do not adjust for the number of comparisons you are making, you will have a probability of making a type-I error that is larger than alpha=.05.

Explanation / Answer

1) True

2) False

3) False

4) False

5) True

6) True

7) False

8) False

9) False

10) False

11) False

12) True

13) False

14) False

15) False

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