Example of a scatterplot with connect line
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Your company manufactures frozen foods and you need to determine the optimal time and temperature for reheating a new frozen entree. You reheat samples at a number of different times and temperatures, then have trained judges rate each for overall quality on a scale of 0 (not enjoyable) - 10 (most enjoyable). Create paneled scatterplots with connect lines to examine the average quality scores for each temperature.

1    Open the worksheet REHEAT.MTW.

2    Choose Graph > Scatterplot.

3    Choose With Connect Line, then click OK.

4    Under Y variables, enter Quality. Under X variables, enter Time.

5    Click Multiple Graphs, then click the By Variables tab.

6    In By variables with groups in separate panels, enter Temp.

7    Click OK in each dialog box.

Graph window output

Interpreting the results

Paneling the graphs allows you view the effects of cooking time on quality separately for each temperature setting. Not surprisingly, optimal cooking times for lower temperatures (top panels) are longer than for higher temperatures (bottom panels). Reheating for too long at the highest temperatures reduces the quality of the product by burning or drying out the food. The optimal time-temperature combination appears to be about 425° for 34 minutes.

Additional examples that help visualize these data include:

·    Scatterplot with connect lines and groups

·    3D scatterplot

·    3D surface plot

·    3D wireframe plot

·    Contour plot