What is the main advantage of testing directional hypotheses (when it is appropriate to do so)?

Question 2 options:

Directional hypotheses can be used even whensis unknown

Directional hypotheses are more likely to reject the null hypothesis than a non-directional test when one is correct about the direction of an effect

Directional hypotheses allow the use of the Z distribution instead of the t distribution

Directional hypotheses are less likely to reject the null hypothesis than a non-directional test when one is correct about the direction of an effect

Question 3(1 point)

The most important difference between the Z andtdistributions is that:

Question 3 options:

Thetdistribution has fatter tails than the Z distribution

Thetdistribution is asymmetrical whereas the Z distribution is symmetrical

The mean of thetdistribution is greater than the Z distribution

Thetdistribution is discrete whereas the Z distribution is continuous

An instructor has developed two forms of a final exam.Each student was given one or the other form at random.The instructor is interested in testing the hypothesis that both forms of the final exam were of the same level of difficulty.What statistical procedure should this instructor use to test his or her hypothesis?

Question 9 options:

At-test for the difference between two population means for independent samples

A Z-test for the difference between two population means for independent samples

At-test for the difference between two population means for matched samples

AnF-test for the significance of variance accounted for by the regression equation

Question 10(1 point)

In a given data set, the coefficient of correlation between variablexand variableyis .6, with variablexbeing the independent variable and variableybeing the dependent variable.What percentage of variation in the dependent variable is explained by the variation in the independent variable?

Question 10 options:

77.46%

66%

36%

24%

Question 11(1 point)

Based on a sample of 200 observations, a 99% confidence interval is calculated to range from 144 to 168.What does it mean to be 99% confident in this interval estimate?

Question 11 options:

Given samples of that size, 99% of the time the calculated interval would contain the population mean

Across repeated samples of that size, the population mean will fall between 144 and 168 99% of the time

99% of the observations in the population from which the sample was drawn fall between 144 and 168

99% of the observations in the sample fall between 144 and 168

Question 12(1 point)

For a lower-tailed test with a 95% confidence level and 50 degrees of freedom, the value oftis:

Question 12 options:

1.96

-1.676

-2.009

+1.676

An investigator has just completed a study using students as subjects.The data were analyzed using ANOVA.The critical value ofFwas given byF_{.05, 5, 14}.How many students were involved in the study?

Question 16 options:

5

14

20

19

You are testing the null hypothesis that the population mean is equal to 200 against the alternate hypothesis that the population mean is not equal to 200.The population standard deviation is 36.You collect a sample of 10 observations; and in this sample, the mean is 210 and the sample standard deviation is calculated to be 25.How would the test statistic be distributed?

Question 18 options:

a xsquared distribution with 9 degrees of freedom

A Z distribution

An F distribution with 9 degrees of freedom in the numerator and 10 agrees of freedom in the denominator

a t distribution with 9 degrees of freedom