Probability and Statistics > Regression Analysis > Construct a Scatter plot

Construct a Scatter plot: Overview

A scatter plot gives you a visual idea of what is happening with your data. Scatter plots are similar to line graphs. The only difference is a line graph has a continuous line while a scatter plot has a series of dots. Scatter plots in statistics create the foundation for simple linear regression, where we take scatter plots and try to create a usable model using functions. In fact, all regression is doing is trying to draw a line through all of those dots!

Watch the video or read on below:

If you want to construct a scatter plot by hand, read on for the steps. However, if you have access to some kind of technology (like Excel), it’s much easier! Follow a link to make a:

• SPSS Scatter plot
• Scatter plot in Minitab
• TI 89 Scatterplot
• Scatter plot in Microsoft Excel
• TI 83 Scatter plot

There are just three steps to creating a scatter plot by hand.

Construct a Scatter plot: Steps

Sample question: create a scatter plot for the following data:

x	y
3	25
4.1	25
5	30
6	29
6.1	42
6.3	46

Step 1: Draw a graph. Label the x- and y- axis. Choose a range that includes the maximums and minimums from the given data. For example, our x-values go from 3 to 6.3, so a range from 3 to 7 would be appropriate.

Step 2: Draw the first point on the graph. Our first point is (3,25).

Step 3:. Draw the remaining points on the graph.

That’s it!

How to Construct a Scatter Plot in Excel

In this section, I’ll cover how to make a scatter plot in Excel plus some advanced options like formatting your chart, adding labels, and adding a trendline (the linear regression equation). Watch the video or read the steps below:

Steps

Step 1: Type your data into two columns.
Step 2: Click “Insert,” then click “Scatter.”
Step 3: Choose a type of plot. For example, click the first icon (scatter with only markers).

Formatting

Delete the Legend.

Step 1: Right click on the legend, then press “delete.”

Clean up the White Space

Sometimes your markers will be clustered at the top or bottom right of the graph. Here’s how to get rid of that white space by formatting the horizontal and vertical axes.
Step 1: Click the “Layout” tab, then click “Axes.”
Step 2: Click “Primary Horizontal,” then click “More Primary Horizontal Options.”
Step 3: Click the “Fixed Value” radio button and then type in a value for where you want your horizontal axis to start. Click “Close.”
Step 4: Repeat Steps 1 to 3, choosing “Vertical” instead of horizontal.

Adding Chart Labels

Excel usually adds labels you don’t want, or leaves out axis labels you do want. To delete unwanted labels, you can click and delete. Here’s how to add a label:
Step 1: Click the “Layout” tab.
Step 2: Click “Axis” titles and then click “Primary Horizontal Axis Title.”
Step 3: Choose a position. for example, you may want the title below the axis.
Step 4: Click the text and type in your new label.
Step 5: Repeat Steps 1 to 4, choosing “vertical” for the vertical axis.

Tip: If you don’t like the vertical arrangement of the axis title, right click, then choose “format axis title.” Click “alignment” and then pick a text direction (i.e. horizontal).

Adding a Trendline

Step 1: Click the “Layout” tab.
Step 2: Click “Trendline” and then click “More trendline Options.”
Step 3: Click the “Show equation on chart box” and then click “Close.”

Scatter plot in Minitab

Watch the video for how to create a scatter plot in Minitab or read the steps below.

Step 1: Enter your data into two columns. One column should be the x-variable (the independent variable) and the second column should be the y-variable (the dependent variable). Make sure you put a header for your data in the first row in each column — it will make the creation of the scatter plot easier in Step 4 and Step 5.

Step 2: Click “Graph” on the toolbar and then click “Scatter plot.”

Step 3: Click “Simple” Scatter plot. In most cases, this is the option you’ll use for scatter plots in elementary statistics. You can choose one of the others (such as the scatter plot with lines), but you’ll rarely need to use them.

Step 4: Click your y-variable name in the left window, then click “Select” to move that y-variable into the y-variable box.

Step 5: Click your x-variable name in the left window, then click “Select” to move that x-variable into the x-variable box.

Step 6: Click “OK” to create the scatter plot in Minitab. The graph will appear in a separate window.

Tip: If you want to change the ticks (the spacing for the x-axis or y-axis), double-click one of the numbers to open the Edit Scale box, where you can change a variety of options for your scatter plot, including ticks.

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