In Excel 2007, if you apply a fourth-order polynomial to any set of X-Y data
on a scattergram AND force the intercept through 0, the correct fitting
equation is displayed. However, when you re-load the workbook after a save,
the fourth order term is completely removed from the equation that is
displayed on the chart. This can lead to incorrect results if subsequent
calculations depend upon the displayed equation (the underlying 4th order
equation that fits the trendline appears to be OK, it is only the equation
displayed that is incorrect). The problem doesn't occur if you do not force
through zero and does not occur in Excel 2003.

You can confirm this bug with any set of X-Y data you wish to create. A
similar bug has been noted on the web since January, I think, but I cannot
find any site to indicate that Microsoft has addressed the issue.
--
rday

----------------
This post is a suggestion for Microsoft, and Microsoft responds to the
suggestions with the most votes. To vote for this suggestion, click the "I
Agree" button in the message pane. If you do not see the button, follow this
link to open the suggestion in the Microsoft Web-based Newsreader and then
click "I Agree" in the message pane.

http://www.microsoft.com/office/comm...lic.excel.misc

This is a know bug that has been reported to the Excel Development team.
However, it seems that it does not always happen so I am collecting samples:
please send me (private email, not to the newsgroup) a file with a chart
that has this problem
many thanks
--
Bernard V Liengme
Microsoft Excel MVP
http://people.stfx.ca/bliengme
remove caps from email

"rday" wrote in message
...

In Excel 2007, if you apply a fourth-order polynomial to any set of X-Y
data
on a scattergram AND force the intercept through 0, the correct fitting
equation is displayed. However, when you re-load the workbook after a
save,
the fourth order term is completely removed from the equation that is
displayed on the chart. This can lead to incorrect results if subsequent
calculations depend upon the displayed equation (the underlying 4th order
equation that fits the trendline appears to be OK, it is only the equation
displayed that is incorrect). The problem doesn't occur if you do not
force
through zero and does not occur in Excel 2003.

You can confirm this bug with any set of X-Y data you wish to create. A
similar bug has been noted on the web since January, I think, but I cannot
find any site to indicate that Microsoft has addressed the issue.
--
rday

----------------
This post is a suggestion for Microsoft, and Microsoft responds to the
suggestions with the most votes. To vote for this suggestion, click the "I
Agree" button in the message pane. If you do not see the button, follow
this
link to open the suggestion in the Microsoft Web-based Newsreader and then
click "I Agree" in the message pane.

http://www.microsoft.com/office/comm...lic.excel.misc