How can I fix round-off errors in Excel when using trendline equations?

[wjp1982]

Hi, I am attempting to find an equation to fit a curve that I have plotted in Excel. I use the trendline function and get an equation but when i place that formula in excel and with the values they are different. I have attached the spreadsheet to show you. The yellow columns are my original data. The blue columns are the numbers i get from the trendline equation. My R-squared value is 1.0 for both too. Any help is beneficial thanks.

 

[TheoMcCloskey]

You are most likely suffering from round-off errors. You are using the displayed coefficients in your formula, however, those displayed coefficients are only showing one significant digit.

Increase the number of displayed digits in the trendline label (right click label, select "format data labels", set Number tab, select Scientific, select number of digits - use at least three).

The displayed coefficients will reveal themselves with more precision. Use these coefficients in your formula.