Trendline Showing Problem ?

[Bob]

Hello,

Let me describe my adding of a Trendline problem (Excel 2007), and what
I found out after extensive experimentation.

I can't understand why this is the cure, and would be most appreciative
for any comments on.

A little background first:

Had to install a new HD as old one conked out in HP Desktop.
Used the 3 System Restore Disks that I created when I got the PC, and,
amazingly, everything works, pretty much, again.
Also re-loaded Excel 2007 from my MS Disc.

From what I can see, Excel works just fine again, like it used to,
except for one problem.

No matter what I do, or try, I can not get it to display a linear Trendline.

I can get all the menus that relate to Trendlines to come up, but
nothing I do will actually show them on the chart that I created from
some quite simple data.

The data for the Chart I have is just two columns. in Col A are dates,
from Jan 1 to Dec. 31.
Next to many of these dates, BUT NOT ALL, is a numerical value.

X axis is dates, Y axis is the numerical value.

Chart (a Scatter) plots up fine. But it will not generate a Trendline,
like it used to without any problem.

Have tried just about everything I can think of. Played with ALL the
Trendline menus and options, etc.

Older Charts I generated show up fine, now, but without the Trendline
that used to be there.

Sure seems like a "funny" thing not to be working when everything else
in Excel now seems to work fine.
Can't help but think that I have something simply configured
incorrectly, not checked off, or...?
Hi again,

But:

If I:

go to: Select Data
Hidden And Empty Cells
Show Empty Cells As Gaps box checked
Then, The Trendline Shows Up O.K.

But, if I check the box for: Connect Data Points With Line, the
Trendline then disappears.
And, will not allow being generated if this box remains checked.

Why ?
I am 99.9% certain that before the hd and Excel re-installs,
it did not act this way. I remember that I always had lines drawn
between the actual data points,
and would merely skip dates for which I had no data; trendlines would
still appear and be drawn; no problem. But, I admit, I might be wrong,
although i don't think so. But, at my age,...!

Again, using Excel 2007, and scatter charts.

My data looks like this:
Col A Col B
Jan 1 5
Jan 2 6
Jan 3
Jan 4 4
Jan 5 8

Many of the dates have no data in Col. B (as shown for Jan 3)

The same problem, though, if there is data next to each date.

The same problem if the dates skip around a bit, like Jan 3, Jan 15, Jan
18, but each date does have data

Any thoughts on ?

Thanks,
Bob

 

[joeu2004]

Any thoughts on ?

My thoughts are: for problems of this nature, it would behoove you to
provide a concrete example.

Ideally, upload an example Excel file to a file-sharing website, and post
the URL of the shared file in a response here. The following is a list of
some free file-sharing websites, if you do not already have a favorite.

Box.Net: http://www.box.net/files
Windows Live Skydrive: http://skydrive.live.com
MediaFire: http://www.mediafire.com
FileFactory: http://www.filefactory.com
FileSavr: http://www.filesavr.com
RapidShare: http://www.rapidshare.com

Alternatively, at least post the data here, if the situation is relatively
simple.

go to: Select Data
Hidden And Empty Cells
Show Empty Cells As Gaps box checked
Then, The Trendline Shows Up O.K.

But, if I check the box for: Connect Data Points With Line,
the Trendline then disappears.
And, will not allow being generated if this box remains checked.

My suspicion is: this has nothing to do with your re-installation. AFAIK,
Excel does not keep a global record of chart options used previously.

(The operative phrase is "global record". Certainly, selected chart options
are retained in the Excel file itself.)

Instead, I suspect this is merely a coincidence. "What changed" is the
data, not so much the re-installation.

In any case, my suspicion is: the root cause of the problem has to do with
the y-axis scale and the fact that there are gaps in your data, compounded
by the numerical range of x-axis data. (Current dates are represented by
large integers; for example, today is 41,609.

Arguably, that does not explain why the trendline might appear with
scattered data points, but not when you connect them with a line. But I
suspect the latter caused a side-effect that you overlooked.

In any case, without a concrete example, my comments are wild speculation.

 

[Ron Rosenfeld]

Older Charts I generated show up fine, now, but without the Trendline
that used to be there.

If there isn't some subtle change in the data, this makes me wonder if a printer (or possibly a video) driver did not get reinstalled properly.

 

[Bob]

Hello,

Just a quick thanks, as always, for all the help.
Much appreciated.

Something must have gotten corrupted, as I just copied all my data to a
new spreadsheet I opened up, and all
seems to work fine in this new one.

So, thanks again,
Bob
-------------------------------------------