1. A two sample z or t test is used to test:

A. whether two samples are from the same population or whether the means of two samples are significantly different

B.whether the mean of differences is significantly higher than both sample means

C.whether the population variance is normally distributed

D.whether the mean of a sample is significantly greater or less than the population mean

E.whether the mean of a sample is different from its population

2. You are performing a two-tailed, two-sample z-test.Your calculated test statistic [z test statistic] is negative.What does this mean?

A.This means there is a negative, indirect relationship between both of your samples.As one variableincreases, the other variable decreases

B.This is not a problem since you are using a two-tailed test. This is an indication that your sample 2 mean was higher than your sample 1 mean

C.Your critical tail region was on the wrong side of the curve. You must redo your test.

D,This means that you must use the population standard deviations instead of the population variances in solving the equation

3.To find the degrees of freedom in a two-sample (independent sample) t test, you would:

A.subtract the number of cases in both samples and then add 1.

B.add the number of cases in both samples and then subtract 1.

C.subtract the number of cases in both samples and then add 2.

D.add the number of cases in both samples and then subtract 2.

4.You run your two-sample t-test.The results are significant at both the 5% and 1% level.What does this tell you?

A.You have a statistically significant result.The probability of NOT rejecting your null hypothesis [and rejecting your alternate hypothesis] is higher at the 1% level than the 5% level so you have more confidence in the results of the test at 1%

B.The probability of rejecting your null hypothesis is higher at the 1% level than the 5% level so you can have more confidence in the results of the test at 5%.

C.You need to increase your sample size and your population N

D.The sample variances and the sample size is large

5.Which of the following scenarios could BEST be tested with a matched pairs or dependent samples t-test? Choose the BEST answer.

A.When you want to compare mean number of hurricanes in both El Nio and La Nia years

B.When you want to see if there is a statistically significant relationship between increased urbanization and an increase in deaths from hyperthermia

C.When you want to see if there is a difference in the number of people who evacuate for a hurricane after a public education campaign (compared to before the campaign)

D. When you want to compare average surface temperatures over two nearby forests: one planted in pine trees and the other planted in maple trees

6.You are reviewing a study that looks at the relationship between lightning strikes and tornadic potential in a thunderstorm.The study has looked at 4 regions giving a p-value for each.For which region would you have the greatest confidence (in the results)?The data are as follows:

SE USA: p = 0.052

Midwest: p = 0.034

Southern Plains: p = 0.017

Northern Plains: p = 0.028

A.SE USA

B.Midwest

C.Southern Plains

D.Northern Plains

7.You are doing a two-tailed test to see if there is a statistically significant difference between mean January snowfall in New York during the N- vs. the P+ phase of the NAO. You calculate a test statistic of -3.47. Your critical value is 1.753.You may reject your Null Hypothesis and infer that there is a statistically significant difference in mean January snowfall.

True

False

8.At a given level of significance (e.g. 5%), the z- or t- critical values in two-tailed tests are:

A.less than in one-tailed tests

B.greater than in one-tailed tests

C.the same as in one-tailed tests

D.it depends on the standard deviation of the population

9.The smaller the significance level, the greater your chances are of rejecting your null hypothesis.

True

False