Chapter 11: Correlation and Regression

If the dots on a scatterplot generally extend from the bottom left to the upper right of the diagram but are very widely spread out, the researcher would report the correlation as:

Weak and positive

The relationship in this scatterplot is…

nonlinear

What is the minimum level of measurement to calculate a Pearson’s r correlation coefficient?

Interval

What is the non-directional null hypothesis for correlation?

r = 0 (or rho = 0)

What is the predicted value of Y when X = 10 using this regression equation?

Y = 30 - 1.2*X

18

Correlations (using the Pearson product moment correlation coefficient) may be uninterpretable and inappropriate if the data...

have a nonlinear relationship.

The difference between a predicted Y score and an actual observed Y score is known as the...

residual.

If the dots on a scatterplot are spread out randomly, the researcher would report the correlation as:

Close to zero

Which of the following is an impossible value for R²?

1.10

If the mean of X is 42, the mean of Y = 72, and r_xy= 0, then what is the predicted value of Y when X = 30?

72

Which of the following is true about regression towards the mean?

All of the answers are correct

When people who score low on one variable tend to score low on another variable, then those two variables...

are positively correlated.

If X and Y in a regression equation are both expressed as z scores – z_X and z_Y – and the correlation between the two variables is r = .3, then what is the predicted value of z_Y when z_X = - 1.2?

-0.36

If X and Y in a regression equation are both expressed as z scores –and– then what can never happen?

zy > zx

If a person has a middling score on X but a very high score on Y, what would their effect on the regression equation be?

They would raise the intercept but not change the slope

Which of the following illustrates a negative correlation?

The more often a person visits the dentist, the fewer cavities they have.

If r = .65, then the members in a sample who have _____ values on the independent variable have _____ values on the dependent variable.

Lower, lower

What is the predicted value of Y when X = 120 using this regression equation?

Y = -350 + 5*X

250

The vertical distance between a person’s predicted score on Y and their actual score on Y is called _____ and it signifies _____.

the residual; error in prediction

Which statistic is defined as the proportion of variance accounted in the dependent variable by the independent variable?

R-squared

If the dots on a scatterplot generally extend from the top left to the bottom right of the diagram but are very widely spread out, the researcher would report the correlation as...

negative but weak.

What is the minimum level of measurement to calculate Pearson’s r correlation coefficient?

Interval

What is the predicted value of Y when X = 20 using this regression equation?

Y = 12 - 0.8*X

-4

When a regression equation doesn’t predict a person’s score perfectly, then the difference between their predicted score and their actual score is the...

residual.

Which of the following is an impossible value for R²?

-0.1

Which of the following is true about regression towards the mean?

All of the answers are correct

If X and Y in a regression equation are both expressed as z scores – zx and  zy – and the correlation between the two variables is r = -.2, then what is the predicted value of zy when  zx= - 0.5?

0.1

If a regression equation is calculated for a sample of data and then a person who is an outlier on both X and Y is added, what would likely happen to the regression equation?

The new score would likely change both the intercept and the slope

If r = -.4, then the people who have _____ values on the predictor variable generally have _____ values on the outcome variable.

lower, higher

The vertical distance between a person’s predicted score on Y and their actual score on Y is called _____ and it signifies _____.

the residual; error in prediction