Statistics: Chapter 14

False

A scatterplot shows the relationship between two quantitative variables measured on two different individuals.

True

A value of r = -1.5 has to be an error.

Outlier

An individual value that falls outside of the overall pattern of the relationship is called an ___________.

True

Because the value for r is negative, we can say that the direction of the relationship is negative.

True

Computing r as a measure of the relationship between X and Y is misleading for the data in the above scatterplot.

-1 1

Correlation r is a number between _________ and ____________.

True

For these data, all of the products are positive.

X

If there is a distinction between the explanatory and response variables, the explanatory variable should be drawn on the ______________ axis of a scatterplot.

no unit of measure

If we change X from diameter to volume and we change Y from volume to diameter, will the value of r change?

No units of measure

If we change the unit of measure for X from centimeters to feet, will the value of r change?

False

Multiplying the z-score for X by the z-score for Y always gives positive products.

Both quantitative

On the basis of this formula, what type of variables are required for X and Y?

The strength of the relationship increases as r moves from 0 toward -1 or 1. Correlation ignores the distinction between explanatory and response variable. Values of r near 0 indicated a weak straight-line relationship.

Select all that apply. Which of the following are true?

That the statement is incorrect because gender is not quantitative.

Suppose someone claims a strong correlation between salary and gender. What should you conclude?

True

The closer the data points are to the line, the closer r is to either -1.0 or +1.0.

True

The formula for computing r includes z-scores for both X and Y.

True

The more closely the points follow a clear form on a scatterplot, the stronger the relationship between the two variable.

True

The sign on r always denotes the direction of the relationship.

The scatterplot slopes upward from left to right.

Two variables are positively associated when:

Each x and y pair of values comes from the same individual.

What does each dot in the scatterplot represent?

C. Two quantitative variables measured on each individual

What type of data is graphed with a scatterplot?

To check whether the relationship is linear or non-linear.

Why is plotting the data so important before computing r?

very weak

With r = -0.226, how should we describe strength?

moderate

With r = -0.553, how should we describe strength?

negative

With r = -0.553, is direction positive or negative?

False

r is resistant to outliers.