General questions about a Forecast and a Trend

[Doofus1]

1 How different are the results derived from a Trend and a Forecast (if all the data being used are the same) ?

Same X and Y values.

2. When may one be preferred over the other?

3. How useful are they - in real world prediction situations (to what percentage are they likely to be accurate?)

[MrShorty]

Trend and Forecast are both linear regressions, so, all else being equal, the two should give the same result. Because they give the same result, I'm not sure when one would be preferred over the other -- except maybe when the function name helps explain what is happening.

How useful? Like simple linear regression in general, they can be very useful when you want to use a simple linear regression (y=mx+b) to model something. The more linear the raw data, the more "accurate" (whatever that means statistically for your application) they are. If the data are not linear, then these functions are not useful.
TREND() help file https://support.office.com/en-us/art...3-9a7cf7b51ef1
FORECAST() help file: https://support.office.com/en-us/art...4-7ad38bbeda99
linear regression stat lesson: http://onlinestatbook.com/2/regression/intro.html
or: http://stattrek.com/tutorials/regression-tutorial.aspx

[Doofus1]

Thank you.