STAT Chapter 9 Quiz

Suppose that you are interested in the extent to which family responsibilities are related to absences from work. You measured the number of young children living at home as well as the number of work absences in the past year for a sample of 10 employees. The data are shown in the table. Using the information that you see here, calculate the value of the slope. Which of the following values comes closest to your result?

+1.12

Which Pearson's r, -.71 or +.52, is indicative of a stronger relationship? A +.52 B -.71

-.71

Suppose that the calculated value of r between cognitive ability and job performance is 0.73. How much variation in job performance is explained by the variation in cognitive ability?

0.53

The following table contains hypothetical data on respondent age and the number of health conditions from which they suffer. Calculate Pearson's r for these data. (Round your answer to two decimal places)

0.74

Suppose that you have analyzed the relationship between population density and crime rate among 20 American capital cities, and obtain an r = +.28. In order to test the significance of this association, we calculate the value of t. Which of the following figures comes closest to that value? A 0.09 B 4.31 C 1.24 D 2.57

1.24

Your analysis of the correlation between household debt (in $ thousands) and household size (number of persons) yields a result of +.44. Your coefficient of determination tells you that family size explains what % of the variation in family debt (rounded to the nearest decimal place)?

19.4

For the example in the preceding two questions, calculate the Standard Error of the Estimate. Which one of the following values comes closest to your result? A 5.17 B 4.88 C 7.19 D 2.31

2.31

Calculate the intercept for the example in the previous question. Which of the following values comes closest to your result? A 0.080 B 6.33 C 1.59 D 2.64

2.64

You are interested in the relationship between education and income. Your intercept is $6,000 and your slope is $1,500. How much income can we expect to see for an individual with 10 years of education? (Round to the nearest dollar, with no commas.)

21000

Through your sample of homeowners, you obtain a Pearson's r value of -.48 between age and amount of money left owed on their mortgage. What percentage of the variation in the amount owed is explained by age? Express the result as a whole number.

23.0

Using the same data as in the previous question, how much income can we expect to see for an individual with 12 years of education? (Round to the nearest dollar, with no commas.)

24000

A school psychologist tests the reading level and math ability of six new children in her school. Reading level is determined using a standard assessment, with higher scores indicating better ability, and math score is the rank on the assessment, with a rank of 1 being the lowest scoring student. The data are below. Convert the reading scores to ranks so that Spearman's rho can be computed, with the lowest score receiving a rank of 1. Note that there are two reading scores of 17. What rank will each reading score of 17 receive?

4.5

According to your sample above, how many absences from work would we expect to see for a person with two children? (Round to one decimal place)

4.9

Determine the statistical significance of the coefficient from EOC 9.29 using alpha = .05, two-tailed. Match the answers below: 1 df 2 critical value of t 3 calculated value of t

A F D

Results are more likely to be statistically significant ___________. Mark all that apply. Multiple answers: You can select more than one option A The larger the sample size B The stronger the correlation C None of the above

A, B

What direction(s) of relationship do these arrows depict? A The pair on the left is positive and the one on the right is negative B The pair on the left is negative and the one on the right is positive C Both sets are positive D Both sets are negative

Both sets are positive

Select the correct formula for the Pearson correlation coefficient.

C

In statistical language, when random variables are associated, we say that they ____ A Coordinate B Covary C Are constant

Covary

A monotonic association would include all of the following types of association except for ________. A Linear B Curvilinear C Negative D Positive

Curvilinear

A school psychologist tests the reading level and math ability of six new children in her school. Reading level is determined using a standard assessment, with higher scores indicating better ability, and math score is the rank on the assessment, with a rank of 1 being the lowest scoring student. The data are below. Compute Spearman's rho using the ranks determined in 14.29. Match the answers below. 1 Spearman's rho 2 sum of squared differences 3 n

E B C

When converting scores to ranks for use with Spearman's rho, how are tied scores ranked? A Each is assigned the lowest rank possible. B Each is assigned the mean of the ranks that they would have held if they had not been tied. C Each is assigned the rank associated with the mean score. D Each is assigned the highest rank possible.

Each is assigned the mean of the ranks that they would have held if they had not been tied.

You have data on the number of years of education and income earned. You would like to examine whether or not they are associated. What would be your first step? A Run a Pearson correlation B Run a regression equation C Produce a scatterplot to look for linearity D Examine the distribution of each variable to look for normality

Examine the distribution of each variable to look for normality

For your statistics assignment, you need to calculate a correlation coefficient. You calculate a Pearson Correlation coefficient of .27 between Gender and Income. Would you pass or fail your assignment? A Pass B Fail

Fail

In reference to the test done in EOC 9.31, comparing the critical value of chi-square to the calculated chi-square leads to which statistical decision? A Reject the null hypothesis. B Fail to reject the null hypothesis.

Fail to reject the null hypothesis

An advantage of Spearman rank correlation is that unlike Pearson correlation, you can use non-random samples. A True B False

False

Both correlation and regression allow us to make specific predictions about what the value of y will be for any given value of x. A True B False

False

What is the interpretation of the Spearman's rho found in EOC 9.29? A It indicates that there is a strong negative relationship between reading level and math scores for these students. B It indicates that there is a weak positive relationship between reading level and math scores for these students. C It indicates that there is a weak negative relationship between reading level and math scores for these students. D It indicates that there is a strong positive relationship between reading level and math scores for these students.

It indicates that there is a strong positive relationship between reading level and math scores for these students.

Suppose that for 18 df and a .05 significance level, the critical value of t in the above example is 2.101. Is the association in the previous question significant or not? A Significant B Not significant

Not significant

Which one of the following is not a requirement for Pearson correlation? A Normally distributed variables B Data measured at the interval or ratio level C Systematic sampling D A linear association

Systematic sampling

"Statistical significance" refers to ________. A The extent to which the results are meaningful B The probability of obtaining the given results if the null hypothesis is true C The likelihood that the results are important

The probability of obtaining the given results if the null hypothesis is true

In reference to the decision made in EOC 9.32, what is the interpretation of the results of the hypothesis test? A There is a significant positive relationship between reading level and math scores. B There is a significant negative relationship between reading level and math scores. C There is no significant relationship between reading level and math scores.

There is no significant relationship between reading level and math scores.

Pearson correlation requires random sampling. A True B False

True

According to our findings in the previous question, should we accept or reject the null hypothesis at p<.05?

accept

Whether or not one set of scores tends to increase or decrease alongside another set without changing to a different trend is known as ____

monotonicity

Using the data from the previous two questions, what is the direction of r?

positive

A correlation is one in which an association between two variables is caused by a third variable that affects both of the other two variables at the same time. A spurious B significant C non-significant

spurious

In a scatterplot, the horizontal line is the A Intercept B x-axis C y-axis D z-axis

x- axis