Chapter 9 Quiz

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

-.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?

.53

A monotonic association would include all of the following types of association except for ________.

Curvilinear

When converting scores to ranks for use with Spearman's rho, how are tied scores ranked?

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?

Examine the distribution of each variable to look for normality

Which one of the following is not a requirement for Pearson correlation?

Systematic sampling

Which of the following scenarios illustrates a spurious correlation?

The more firefighters who arrive at a fire, the greater the fire damage

"Statistical significance" refers to ________.

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

What direction(s) of relationship do these arrows depict?

both sets are positive

In statistical language, when random variables are associated, we say that they

covary

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?

fail

A correlation coefficient distinguishes between independent and dependent variables.

false

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

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.

false

The standard error of the estimate is a summary statistic that expresses our overall degree of error in predicting values of x based on values of y.

false

There is no such thing as a zero correlation.

false

pearson's r

grade point avg and number of hours worked per week

lambda

hair color and occupation

point biseral

iq and politcal party affiliation

spearman's rho

job performance ranking and job satisfaction ranking

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

monotoncity

When a set of x and y values increase or decrease together but never increase and subsequently decrease together, we say that they are

monotonic

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?

not significant

y hat

our predicted value of the response or the outcome variable

Suppose that you have access to hospital records on patient age and their number of days spent in hospital. Your most appropriate measure of association would likely be ________.

pearson's r

You decide to ritualistically eat apple cinnamon oatmeal for breakfast on exam days because you got an "A" on your statistics exam on a day that you had consumed a large portion of it. This is an example of what sort of reasoning?

post hoc

One of the requirements for Pearson's r is that a sampling method should be used.

random

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.

spurious

Sort the following steps for testing the significance of a correlation.

state the claim specify identify calculate compare interpret

a

the intercept

b

the slope of regression line or its steepness

x

the value of the predictor variable

Pearson correlation requires random sampling.

true

In a scatterplot, the horizontal line is the

x axis

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

Results are more likely to be statistically significant ___________. Mark all that apply.

A The larger the sample size B The stronger the correlation