This page includes Step-by-Step instructions to use Excel to find an approximating curve for the Water/Temperature example.  

Note: If you have never used Microsoft Excel, then you may want to try the Introduction to Excel tutorial.

Example: Assume that during a three-hour period spent outside, a person recorded the temperature and their water consumption.  The data was collected on 7 random days during the summer.

Use MS Excel to find an equation of an approximating curve to express the relationship between Temperature and Water Consumption.

Step-by-Step Instructions, based on this example.

Preliminaries:  The links below are for help with the preliminaries.

• Entering Data in MS Excel
• Drawing a Scatterplot using MS Excel
  

Procedure:  Adding a Trend Line to a Scatterplot.

1. Enter the Water/Temperature Data.
2. Draw a Scatterplot with the  Temperature on the horizontal axis and Water Consumption on the vertical axis.
3. Right click on the data points of the graph.  All points should be highlighted.
4. Select Add Trendline.

   	Click on the Type tab. Select Trend/Regression Type to be Linear and Based  on series should be the Water Consumption variable.
   	Click on the Options tab.

   • In the Trendline Name section mark Automatic.
   • In the bottom section, mark Display equation on chart and Display R-squared value on chart.
   • Click  OK.
   Click on the resulting equation and move it, so that it is readable.

• Click here for a linear solution.

Note:  As you can see in the Add Trendline - Type dialog box, Excel will fit the curve of many different types of relationships.  Click below for examples.

• Linear
• Logarithmic
• Polynomial (set the Order to 2 for Quadratic, 3 for Cubic, 4 for Quartic, ...)
• Power
• Exponential, and 
• Moving Average (set the Period) 

Go to the  Algebraic Review of Functions Page for more basic shape examples.  This review page has a lot of images.  You may prefer to see each type of equation individually. 

Linear  Quadratic  Cubic  Quartic  Exponential  Logarithmic  Sinusoidal

Learn the Curve Fitting Procedures

or quiz yourself on the Curvefitting Terms

Curvefitting Menu

Return to Regression Level I Menu    Dictionary   

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