Download Example 3.1

Example 2.7
Relationship Between Salaries and
Domestic Gross for Movie Stars
Analyzing Relationships with Scatterplots
Objective
To use StatPro’s scatterplot procedure to
illustrate the relationship between movie
gross and actor salary.
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ACTORS.XLS

Recall that this data set contains information on 66
movie stars including their, Gender, Domestic Gross,
Foreign Gross and Salary.

The data may lead us to suppose that stars whose
movies gross large amounts have the largest
salaries. Is this true?
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Scatterplots

We are often interested in the relationship between
two variables.

A useful way to picture this relationship is to plot a
point for each observation, where the coordinates of
the point represent the values of the two variables.

The resulting graph is a scatterplot.
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Scatterplots -- continued

After constructing a scatterplot, we can examine the
scatter of points.

We can usually see whether there is any relationship
between the two variables, and, if so, what type of
relationship it is.

We will use a scatterplot to determine if the statement
about the relationship between movie gross and
salaries is true.
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Creating a Scatterplot

To analyze this we need to plot each star’s salary on
the vertical axis and the corresponding domestic
gross on the horizontal axis.

To create this scatterplot:
– Place the cursor anywhere in the data set.
– Select the StatPro/Charts/Scatterplot menu item.
– Select Salary as the Y variable, Domestic Gross as the X
variable and give the chart sheet a name such as Scatter.
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The Resulting Scatterplot
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Analyzing the Scatterplot

The message is clear. The points tend to move up
and to the right. This means that stars in films with
large domestic grosses tend to make the largest
salaries.

The correlation of 0.61 shown in the chart supports
this conclusion. As we will see in Chapter 3, this
implies a reasonably strong positive linear
relationship between the two variables.
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