Newbie trouble with polynomial trendline equation



This is the polynomial trendline equation I generated from a series of data
items. I've been trying for hours to write the equation properly in my
cells, but I do not seem to be doing it right. I'm a newbie at excel.

y = -3E-08x6 + 1E-06x5 - 4E-05x4 + 0.0005x3 + 3E-05x2 + 0.0101x - 0.0048
R2 = 1

Where x = percentage of job duration (B171/$D$165) (ex: .05)
and y = percentage of allotted hours used (ex: .006)



What am i doing wrong?... I'm getting negative numbers after plugging the
equation into my spreadsheet, so obviously I am re-writing the equation
wrong... Thoughts?

Mike Middleton

Medusa -
What am i doing wrong? <

You could use Excel's 15 significant digits to obtain better results (by
selecting the trendline equation and clicking the Increase Decimal key
Thoughts? <

Use Google to search for "excel polynomial regression overfit" (without the

After reading some of those items, if you still want to use a sixth-degree
polynomial, use worksheet functions, described by John Walkenbach at

- Mike

Tushar Mehta

If you have a reason to believe that a 6th order polynomial is the way
to go, fine but that is rarely the case.

For options on how to get coefficients into a worksheet see
Trendline Coefficients and Regression Analysis
Tushar Mehta
Custom business solutions leveraging a multi-disciplinary approach
In Excel 2007 double-click to format may not work; right click and select
from the menu

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