Linest and chart trendline show different results

[Victor0nl1n3]

Hello Friends!

Here's the issue...

I have real monthly figures for 9 periods.

1) I put them in a graph and generate a trend line using the polynomial order 3 tool

I want the numbers for the next 10 periods using this trend line.

2) I use the linest function, specifying that I want degree 3 to calculate the relevant coefficient.

I then calculate the the values based on the linest coefficient and put these figures in the graph. The problem is that this new line doesn't fit at all the line in 1) although they should be the same!!

Any ideas??

Thank you

 

[joeu2004]

Crossposted at http://www.excelguru.ca/forums/showthread.php?7055-Linest-and-chart-trendline-show-different-results (click here). See my responses there.