AP Stats Correlation Test

Suppose the correlation between two variables is r=.28. What will the new correlation be if .17 is added to all values of the x variable, every value of the y-variable is doubled, and the two variables are interchanged?

.28

If every dog married a cat exactly three years younger than them, what would be the correlation between the ages of the married dogs and cats?

1

.Which of the following statements about the correlation r are true. 1. The correlation and the slope of the regression line always have the same sign. 2. A correlation of -.32 and a correlation of +.32 show the same degree of clustering around the regression line. 3. A correlation of .78 indicates a relationship that is 3 times as linear as one for which the correlation is .26.

1,2

Which of the following are true statements about the correlation coefficient r? 1. Is it not affected by changes in the measurement units of the variables. 2. It is not affected by which variable is called x and which is called y. 3. It is not affected by extreme values.

1,2

Suppose the correlation is negative. Given two points from the scatterplot, which of the following is possible? 1. The first point has a larger x value and a smaller y value than the second point. 2. The first point has a larger x value and a larger y value than the second point. 3. The first point has a smaller x value and a larger y value than the second point.

1,2,3

Suppose a study finds that the correlation coefficient relating job satisfactory to salary is r=1. Which of the following are proper conclusions? 1. High salary causes high job satisfaction 2. Low salary causes low job satisfaction 3. There is a very strong association between salary and job satisfaction.

3 only

Suppose the correlation between two variables is .85. If each of the y-values is multiplied by -1, which of the following is true about the new scatterplot?

It slopes down to the right, and the correlation is -.85.

Consider the points (-1,4), (2,10), (4,15), (7,21), and (10,n). What should n be so that the correlation between the x and y values is r=1.

No values for n can make r=1

A study is conducted relating AP Statistics exam scores to the total number of study hours for the AP Statistics class put in by students during the academic year, and the correlation is found to be .6. Which of the following are true statements? 1. On the average, a 40% increase in study time results in a 24% increase in exam score. 2. 60% of a student's exam score can be explained by the number of study hours. 3. Higher exam scores tend to be associated with high numbers of study hours

None of the answer choices gives the complete set of true responses

Which of the following are true statements about the correlation coefficient r? 1. A correlation of .3 means that 30% of the points are highly correlated. 2. The square of the correlation measures the proportion of the y variance that is predictable from a knowledge of x. 3. Perfect correlation, that is, when the points lie exactly on a straight line, results in r=0.

None of these statements are true

A study of weekly hours of television and SAT scores reports a correlation of r=-1.18. From this information we can conclude that:

A mistake in arithmetic has been made.

Which of the following statements about the correlation r are true? 1. When r=0, there is no relationship between the variables. 2. When r=.2, 20% of the variables are closely related. 3. When r=1, there is a perfect cause and effect relationship between the variables.

All the statements are false