The power and exponential trendline options are grayed out (not available) in
my Excel 2003. Why is this and how do I fix it?

The reason why the power and exponential trendline options are grayed out in your Excel 2003 is because your data may not be suitable for these types of trendlines. Power and exponential trendlines are used to show a curved relationship between two variables, and they work best when the data points are spread out evenly on a logarithmic scale. If your data doesn't meet these requirements, Excel won't allow you to use these trendline options.

However, if you believe that your data is suitable for these types of trendlines, you can try the following steps to fix the issue:

1. Make sure that your data is formatted correctly. The x-values should be in one column and the y-values should be in another column. Also, make sure that there are no blank cells in your data.
2. Select the chart that you want to add a trendline to.
3. Right-click on one of the data points in the chart and select "Add Trendline" from the context menu.
4. In the "Trendline Options" dialog box, select "Power" or "Exponential" from the "Type" drop-down menu.
5. If the options are still grayed out, try changing the "Order" value to a higher number. This will increase the degree of the polynomial equation used to fit the trendline to your data.
6. If none of these steps work, it's possible that your version of Excel may not support these trendline options. In that case, you may need to upgrade to a newer version of Excel or use a different software program that supports these types of trendlines.

jemelland -

The power and exponential trendline options are grayed out (not available)
in my Excel 2003. Why is this and how do I fix it? <

Here are some edited excerpts from my book "Data Analysis Using Microsoft
Excel: Updated for Office XP":

The power model creates a trendline using the equation
y = c * x^b.
Excel uses a log transformation of the original x and y data to determine
fitted values, so the values of both the dependent and explanatory variables
in your data set must be positive. If any y or x values are zero or
negative, the Power icon on the Add Trendline Type tab will be grayed out.
(As a workaround, you can add a constant to each y and x value.)

The exponential model creates a trendline using the equation
y = c * e^(b*x).
Excel uses a log transformation of the original y data to determine fitted
values, so the values of the dependent variable in your data set must be
positive. If any y values are zero or negative, the Exponential icon on the
Add Trendline Type tab will be grayed out. (As a workaround, you can add a
constant to each y value.)

- Mike
http://www.MikeMiddleton.com