so234 ch 13

If we calculate an r of .60, the proportion of the variation of Y that is explained by X is... a. .36 b. .40 c. .60 d. .64

a. .36

***If the regression line showing the effect of education on income has a slope of 1000,... a. the variables are not related. b. every year of education increases income by 1000. c. every change in education increases income. d. the Y intercept would be 1.00.

b. every year of education increases income by 1000.

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

b. the best fitting regression line.

***If a regression line is parallel to the horizontal axis of the scattergram, the slope (b) will be... a. 1.00. b. -1.00. c. 0.00. d. 0.45.

c. 0.00.

If a = 5 and b = 10, what would the value of Y be when X = 100? a. Unknown, more information is needed b. 1000 c. 1005 d. 5001

c. 1005

The appropriate measure of association for situations in which both variables are interval-ratio in level of measurement is... a. Pearson's r. b. gamma. c. chi square. d. the slope (b).

a. Pearson's r.

***If the slope of a regression line is 1.5, then... a. for every unit of change in X, there is a change of 1.5 units in Y. b. for every unit of change in Y, there is a change of 1.5 in X. c. the score of each case is 1.5 times higher on Y than on X. d. Y causes X

a. for every unit of change in X, there is a change of 1.5 units in Y.

***There is no linear relationship between two interval-ratio variables when the regression line on a scatter plot... 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.

a. is parallel to the horizontal axis.

***One key assumption of correlation analysis is that the variables have an essentially BLANK relationship. a. linear b. non-linear c. curvilinear d. circular

a. linear

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

a. positive when the line slopes upward from left to right.

***After scores of all cases have been located on a scatter plot, a straight line drawn so that it comes as close as possible to touching every score is called the... a. regression line. b. line of approximation. c. cluster line. d. scatterplot summary.

a. regression line.

***Visual examination of a scatterplot indicates the existence of an association between variables when... 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.

a. the distribution of Y changes as X changes.

The amount of error in predicting Y that remains after X has been taken into account is... a. the unexplained variation of Y. b. r -1.00. c. always zero. d. r.

a. the unexplained variation of Y.

When working with interval-ratio data, the optimal strategy for predicting Y while taking X into account would be to... a. use the regression line. b. guess randomly. c. ignore the slope (b). d. always predict the Y intercept (a).

a. use the regression line.

By convention, the dependent variable is arrayed along the BLANK in a scatterplot. a. vertical axis (the ordinate) b. regression line c. horizontal axis (the abscissa) d. calibration line

a. vertical axis (the ordinate)

A research project found that in studying the effects of days spent in drug rehabilitation and number of subsequent arrests,that the slope was -0.59 and the intercept was 6.13. If a person spends 3 days in rehabilitation, what would be their predicted number of future arrests? a. 2.37 b. 4.36 c. 6.32 d. 7.90

b. 4.36

If a = 2 and b = 4, what would the value of Y be when X = 1? a. 4 b. 6 c. 2 d. 1

b. 6

***A perfect association between variables can be seen on a scatter plot when... 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.

b. all dots lie on the regression line.

A study found that parenting classes were closely related to a child's performance in school. Each week of parenting classes taken by a child's parents raised their high school GPA by 0.23 points. With an intercept of 1.68, what could parents who attended 8 weeks of classes expect to see in their child's subsequent GPA? a. 2.52 b. 3.21 c. 3.52 d. 3.79

c. 3.52

On a scatter plot, the regression line... a. is drawn parallel to the horizontal axis. b. is always perpendicular to the vertical axis. c. comes as close as possible to touching every score. d. touches at least half of the scores.

c. comes as close as possible to touching every score.

***When referring to interval-ratio variables, a commonly used synonym for association is... a. probability. b. predictability. c. correlation. d. causation.

c. correlation.

***By convention, the independent variable is arrayed along the BLANK in a scatterplot. a. vertical axis (the ordinate) b. regression line c. horizontal axis (the abscissa) d. calibration line

c. horizontal axis (the abscissa)

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

c. mean Y score for every case.

***The position of the least-squares regression line is defined by two elements: 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. the Y intercept and the slope of the line.

In regression analysis, the symbol "a" stands for... a. the scores on the Y variable. b. the slope. c. the Y intercept. d. the X intercept.

c. the Y intercept.

The explained variation represents... 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.

c. the improvement in our ability to predict Y when taking X into account.

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

c. the mean of the conditional Y scores.

A researcher wants to measure the strength of the association between income (measured in dollars per year) and education (measured in number of years of formal schooling). Which of the following would be the most appropriate measure of association? a. The slope (b) b. Gamma c. Chi square d. Pearson's r

d. Pearson's r

Scatterplots give information about the BLANK of a relationship. a. strength b. direction c. linearity d. all of the above

d. all of the above

***If the slope (b) is zero, the value of r... a. would also be zero. b. would be 1.00. c. would be - 1.00. d. cannot be determined from the information given.

d. cannot be determined from the information given.

***One important function of the least-squares regression equation is that... 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. it allows us to predict Y scores for any value of X.

***The slope (b) is an awkward measure of the strength of a relationship because... a. it varies from 0 to 1.00. b. it decreases in value as the relationship increases in strength. c. it can have a negative sign when the relationship is actually positive. d. its upper limit is greater than 1.00.

d. its upper limit is greater than 1.00.

If the regression line on a scatter plot slopes upward from left to right, the relationship is... a. bivariate. b. strong. c. parallel. d. positive.

d. positive.

The symbol Y' ("Yprime") stands for... 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.

d. the predicted score on Y.

The Y intercept is the point where... 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.

d. the regression line crosses the vertical axis of the scattergram.