Forecast and trend does not yield same result

It is because you are comparing apples and oranges.

The TREND function returns the same result as the original FORECAST function. Enter =FORECAST(Table1[@Timeline],$B$2:$B$47,$A$2:$A$47) into H2 and =H2-G2 into I2 formatted as Scientific. Copy H2:I2 into H3:I70. The result is 0.00E+00, exact zero, which indicates identical results.

You are using the FORECAST.ETS function +/- the FORECAST.ETS.CONFINT function in rows (47 and?) 48:70. I am not familiar with those functions, since they are not available in my version of Excel. But according to Excel support pages, these functions use ``the AAA version of the Exponential Smoothing (ETS) algorithm`` to estimate results, whereas TREND and FORECAST use linear regression.

So it does not surprise me that they do ``not yield [the] same result``. Whether or not the differences could explain a difference in the slope direction (upward for one; downward for the other), I cannot say. But again, it does not surprise me.


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PS.... Just reread davsth's response, and I see that mine is virtually identical. Sorry about that. I guess the only value-added of my response is the precise formulas for comparing TREND and FORECAST.