A frequency distribution is a table that displays each possible value and the number of times that value occurs.

To investigate whether or not sending text messages while driving impacts driving ability,we had 100 participants (50 men and 50 women)drive an obstacle course under one of the following conditions: 1)no texting while driving,2)sending five text messages while driving,or 3)sending 10 text messages while driving.We measured the accuracy with which the subjects drove the obstacle course from a scale of 1 to 10 (1 = poor and 10 = excellent).What is the treatment in this study?

Typically,the null hypothesis in a test of significance is a statement of "no difference" in the true means.

Which of the following is a property of r,the coefficient of correlation?

A) r always lies between 0 and 1.
B) r has no units.
C) If you switch the values of X and Y,the sign of r changes.
D) All of these choices are true.