Question 1

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 B

Question 2

The position of the least-squares regression line is defined by two elements:

Accepted Answer

A)  the X intercept and the slope of the line.
B)  the X intercept and the Y intercept.
C)  the Y intercept and the slope of the line.
D)  the intersection point of the X and Y axes and the slope of the line. C

Question 3

One important function of the least-squares regression equation is that

Accepted Answer

A)  we can use it to tell if a relationship is linear.
B)  it summarizes all possible scores on the two variables.
C)  it makes the scattergram symmetrical.
D)  it allows us to predict Y scores for any value of X. D

Question 4

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 5

If we calculate an r of .60,the proportion of the variation of Y that is explained by X is

Accepted Answer

A)  .36.
B)  .40.
C)  .60.
D)  .64.

Question 6

After scores of all cases have been located on a scattergram,a straight line drawn so that it comes as close as possible to touching every score is called the

Accepted Answer

A)  regression line.
B)  line of approximation.
C)  cluster line.
D)  scattergram summary.

Question 7

The explained variation represents

Accepted Answer

A)  the conditional distributions of Y.
B)  the amount that Y varies.
C)  the improvement in our ability to predict Y when taking X into account.
D)  the sum of the squares of all scores of Y.

Question 8

In a scattergram,the point of minimized variation for scores of Y for a given value of X (the independent variable)is

Accepted Answer

A)  the sum of the conditional Y scores.
B)  the standard deviation of the conditional Y scores.
C)  the mean of the conditional Y scores.
D)  the predicted Y score.

Question 9

Scattergrams give information about the ____ of a relationship.

Accepted Answer

A)  strength
B)  direction
C)  linearity
D)  all of these

Question 10

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 scattergram.
C)  the regression line meets the conditional mean of Y.
D)  the regression line crosses the vertical axis of the scattergram.

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

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 13

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 14

By convention,the dependent variable is arrayed along the ____ in a scattergram.

Accepted Answer

A)  vertical axis (the ordinate) 
B)  regression line
C)  horizontal axis (the abscissa) 
D)  calibration line

Question 15

A perfect association between variables can be seen on a scattergram when

Accepted Answer

A)  all dots lie an equal distance from the regression line.
B)  all dots lie on the regression line.
C)  the regression line forms a right angle at its intersection with the X axis.
D)  the regression line is parallel to the X axis.

Question 16

A study of traffic safety show a correlation of 0.57 between average speed of traffic and number of fatal accidents for a particular stretch of highway.This means that

Accepted Answer

A)  speed kills.
B)  as speed increases,fatalities decrease.
C)  fatalities tend to increase as average speed increases.
D)  every 1 mile per hour increase in average speed increases the number of traffic fatalities by .57.

Question 17

Visual examination of a scattergram indicates the existence of an association between variables when

Accepted Answer

A)  the distribution of Y changes as X changes.
B)  the regression line is parallel to the horizontal axis.
C)  the regression line is perpendicular to the horizontal axis.
D)  no single regression line can be founD.

Question 18

The appropriate measure of association for situations in which both variables are interval-ratio in level of measurement is

Accepted Answer

A)  Pearson's r.
B)  gamma.
C)  chi square.
D)  the slope (b) .

Question 19

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 these

Question 20

If the slope (b)is zero,the value of r

Accepted Answer

A)  would also be zero.
B)  would be 1.00.
C)  would be -1.00.
D)  cannot be determined from the information given.

Exam 14: Association Between Variables Measured at the Interval-Ratio Level