Statistics Psychology questions!

Question 9

The standard error of the estimate

a. must be negative due to the difference scores that are calculated

O b. is an estimate of the variability of the data points about the regression line

O c. can only be created for regression lines with more than 4 data points

O d. tells us if the regression line is positively or negatively sloped

Question 10

There is a correlation of -.78 between age and criminal activity. This means:

O as age increases, criminal activity increases

O as age decreases, criminal activity decreases

O as age decreases, criminal activity increases

O none of the above

Question 11

A researcher measured stress levels on a 1-10 scale and performance of accountants by

counting the number of errors they made in a week period. Conduct a hypothesis test

using Pearson's correlation coefficient to see if stress was related to performance. Set

alpha a = .05.

What is the null hypothesis in words?

O Accountants make the same number of errors as the general population

O There is a correlation between stress and performance

O Stress and performance are independent

O There is no correlation between stress and performance

Question 19

A researcher rejects a null hypothesis at = .01. What is the probability that the researcher

made a Type I error (assuming that the null is really true)?

O 5%

0 0%

O 1%

0 99%

Question 20

Which of the following is an example of a nominal scale of measurement?

O television station number

0 IQ

O percentage correct on an exam

O weight

Question 21

If you conduct a single-sample t-test with 20 participants with a = .05, two-tailed, what

are your critical values?

1 pts

O 2.093

O 2.861

O 2.086

O 1.729

Question 22

What is the critical value of a two-tailed z-test with a = .05?

0 .0199

O 1.64

O 1.65

O 1.96

Question 23

A percentile is:

O the percentage of a distribution at or above a certain point

O the percentage of a distribution at or below a certain point

O the percentage of a distribution between two mid-points

O the percentage of a distribution below the mean

Question 24

Which of the following is true about z-scores:

O Z-scores expresses the number of standard deviations an observation is from the mean

O b. A distribution of Z-scores always has a mean of zero

O c. A distribution of Z-scores has a different mean than the original raw-score distribution, but will

have the same standard deviation.

O d. Both a and b

Question 25

Which of the following statements is true?

O inferential statistics make inferences about sample statistics

O descriptive statistics allow for inferences about population parameters

O descriptive statistics describe population statistics

O inferential statistics allow for inferences about population parameters