# Trend: Logarithmic and Polynomial

1. ## Trend: Logarithmic and Polynomial

Hi,

I've tried the Trend Function on Cell H3 of the attached file but it was giving me "#Value!" as a result! Also tried putting it as array but to no avail.

Is there any formula that can derive the logarithmic and polynomial Forecast for the coming year in Excel? I can add the trendline on the chart but the line doesn't give me the values on the chart. Anyway, can anyone help to have the 2 Trend numbers on Cell H3 and I3?  Register To Reply

2. ## Re: Trend: Logarithmic and Polynomial

I don't think a logarithmic foecast makes much sense. Things that have a constant percentage Y/Y growth or decline follow an exponential curve. To get a prediction for 2010 that way, use =GROWTH(B3:G3, , 7), where 7 is the next number in the categorical series (2004=1, 2005=2, ...).

The 2009 YTD number has to be corrected (via extrapolation) to a 2009 total in order to be meaningfully used.  Register To Reply

3. ## Re: Trend: Logarithmic and Polynomial

Thanks for the formula to estimate the forecast on exponential curve. However, I still need Logarithmic one as other brands (not mentioned in the table) have both highs and lows during the last 6 years. The Trend Formula is not working on the Sheet as mentioned earlier. But the Logarithmic one would be really useful.

Thanks a lot.  Register To Reply

4. ## Re: Trend: Logarithmic and Polynomial

=trend(b3:g3, ln({1,2,3,4,5,6}), ln(7))  Register To Reply

5. ## Re: Trend: Logarithmic and Polynomial

shg, Thanks for the formula for the logarithmic trend For cell I3, could you please give me the formula for the Polynomial Trend as some brands have seasonal impact in the year.

Thanks heaps. I really appreciate your help.    Register To Reply

6. ## Re: Trend: Logarithmic and Polynomial

No sales follow a poly trend.

You should look up sources for seasonal forecasting.  Register To Reply