Regression and Correlation Methods: Correlation, ANOVA, and Least Squares

Dot Plots and Correlation

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2 Dot Plots and Correlation

Dot Plots

Dot plots give a visual presentation of what happens when we change two variables at the same time.

The following screenshot displays the selection of the procedures in Minitab

First, enter data manually (see below)

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Select the data entered and click on the “Graphs” tab

Click on “Scatterplot” and select the “Simple” scatterplot under the single Y Variable category since we have one x and one y variable to plot

Select the appropriate variable for each variable type.

Click OK.

4 Dot Plots and Correlation

The following screenshot displays the output of Minitab with the scatterplot dot plot

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Correlation

Since we saw a visual representation of the relationship between two variables, now is the time to measure the strength of the relationship.

Highlight the data

Click on “Statistics”

Select “Correlation” and enter the two variables to test for correlation in the box. Click OK.

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Correlations: C1; C2

Pearson correlation of C1 and C2 = 0.791

P-value = 0.006

This means that we have a strong linear correlation (r=0.791).

Statistically significant, with p-value less than 0.05