Question 1

Dummy variables make it possible to include ________ in regression analysis

Accepted Answer

A)  nominal variables 
B)  variables measuring intelligence 
C)  interval-ratio variables 
D)  variables with more than two scores

Question 2

The amount of error in predicting Y that remains after X has been taken into account is

Accepted Answer

A)  the unexplained variation of Y 
B)  r - 1.00 
C)  always zero 
D)  r

Question 3

Scatterplots give information about the _____________ of a relationship.

Accepted Answer

A)  strength 
B)  direction 
C)  linearity 
D)  all of the above

Question 4

If a = 2 and b = 4, what would the value of Y be when X = 1?

Accepted Answer

A)  4 
B)  6 
C)  2 
D)  1

Question 5

The Y intercept is the point where

Accepted Answer

A)  the horizontal axis connects to the vertical axis 
B)  the regression line crosses the horizontal axis of the scatterplot 
C)  the regression line meets the conditional mean of Y 
D)  the regression line crosses the vertical axis of the scatterplot

Question 6

Scatterplots do NOT give information about the _____________ of a relationship

Accepted Answer

A)  strength 
B)  direction 
C)  linearity 
D)  significance

Question 7

The symbol Y' ("Y-prime") stands for

Accepted Answer

A)  the 1st Y score 
B)  the highest score on Y 
C)  the value of Y when X is zero 
D)  the predicted score on Y

Question 8

The direction of a relationship between variables can be detected on a scatterplot by considering the angle of the regression line. The relationship is

Accepted Answer

A)  positive when the line slopes upward from left to right 
B)  positive when the line slopes downward from left to right 
C)  negative when the line slopes upward from left to right 
D)  negative when the line slopes downward from right to left

Question 9

For interval-ratio level variables, the scatterplot is analogous to ___________ for nominal and ordinal level variables.

Accepted Answer

A)  chi square 
B)  percentages 
C)  row marginals 
D)  bivariate tables

Question 10

A researcher reports a Pearson r of .57 between gender (female = 0, males = 1) and involvement in juvenile delinquency. Which of the following is an appropriate interpretation?

Accepted Answer

A)  females are more delinquent 
B)  there is no relationship between the variables 
C)  delinquency increases as gender "increases" 
D)  only males were delinquent

Question 11

For summarizing the relationship between X and Y, the points of minimized variation for the conditional distributions of Y provide us with

Accepted Answer

A)  several regression lines to choose from 
B)  the best fitting regression line 
C)  a regression line that touches all of the dots 
D)  regression lines with negative slopes

Question 12

If a line is drawn through the conditional means of Y, the line will

Accepted Answer

A)  always be perfectly linear 
B)  rarely be perfectly straight 
C)  always be parallel to the horizontal axis 
D)  always be parallel to the vertical axis

Question 13

There is no linear relationship between two interval-ratio variables when the regression line on a scatterplot

Accepted Answer

A)  is parallel to the horizontal axis 
B)  does not touch all of the scores 
C)  is not an equal distance from all of the scores 
D)  is bimodal

Question 14

The conditional mean of Y for any value of X is found by

Accepted Answer

A)  adding the Y scores for the specific value of X and dividing by N 
B)  adding all the Y scores and dividing by X 
C)  subtracting the mean of Y from the overall mean of X 
D)  any of the above

Question 15

When working with interval-ratio data, the optimal strategy for predicting Y while taking X into account would be to

Accepted Answer

A)  use the regression line 
B)  guess randomly 
C)  ignore the slope (b) 
D)  always predict the Y intercept (a)

Question 16

If a regression line is parallel to the horizontal axis of the scatterplot, the slope (b) will be

Accepted Answer

A)  1.00 
B)  -1.00 
C)  0.00 
D)  0.45

Question 17

In a study of the relationship between geographical mobility (number of times a person has changed residences) and number of friends, Pearson's r² is reported as .40. Which of the following would be a correct interpretation?

Accepted Answer

A)  Mobility explains 16% of the variation in number of friends 
B)  There is a strong positive relationship between number of friends and mobility 
C)  As mobility increases, number of friends decreases 
D)  Mobility explains 40% of the variation in number of friends

Question 18

A researcher asked a sample of dual career families about the percentage of the family budget contributed by the wife's job (Y) and the total number of children (X). Pearson's r for this relationship is -0.34. Which of the following is an appropriate interpretation of these results?

Accepted Answer

A)  For every dollar contributed by the wife, the number of children increases by .34 
B)  For every additional child, the wife must work longer hours 
C)  Every additional child lowers the economic wellbeing of the family 
D)  As number of children increase, the percentage of the budget contributed by the wife decreases

Question 19

When working with interval-ratio data, the optimal strategy for predicting Y while ignoring X will be to use the

Accepted Answer

A)  mode of the Y scores for every case 
B)  median Y score for every case 
C)  mean Y score for every case 
D)  lowest Y score for every case

Question 20

When referring to interval-ratio variables, a commonly used synonym for association is

Accepted Answer

A)  probability 
B)  predictability 
C)  correlation 
D)  causation

Exam 12: Association Between Variables Measured at the Interval-Ratio Level