I have a exponential trendline that was generated by excel ("Add Trendline") on a chart.

I've plugged in the equation (from the "Display Equation on Chart" option, up to 14 decimals) into a spreadsheet and compared the projected values with those values projected by the GROWTH and LINEST functions. In my comparison, I noticed that the interpolated values differ.

Can anyone explain how the methods excel uses to derive these trendline equations differ? Is one method more appropriate than the other?

Thank you.

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#### Best Answer

You might edit to show your data. I just entered some data that I made to look exponential-ish, and using Add Trendline (exponential) and GROWTH gave almost exactly the same results. There were only slightly different values, and I'd say that was due to the fact that I only used 4 digits after the decimal point when I displayed the equation on the chart.

This is assuming that you're trying to fit data that is exponential-like. In which case, LINEST would give dramatically different results, since it's trying to fit a straight line. On the other hand, if your data were basically linear and you tried using GROWTH on it, you won't get a very good fit there.