Urgently needed help with backcasting

Hello!

Finishing up my dissertation and my adviser has asked me to "backcast" certain data sets in order to go back further and fill in historical data which isn't available (the logic is that the more data I have, the more well behaved will be the regressions I will perform on such data).

In Excel, I plotted each data set in a separate scatter plot graph, and added linear trendlines. However, I have somehow NOT been able to get the "backward forecast" trendline function to work to fill in data following the first years of data I have. I thought I could perform this myself using the "show formula" (of trendline) function, but for certain data sets, the returned values seem very odd. Thus, I'm not sure if I'm doing something incorrectly or if those really are the results.

Can anyone help with this?

Thanks very much!!

amread

Hi
Have a look at this link which MAY help you.

http://www.spiderfinancial.com/suppo...kward-forecast

Good luck.
Tony