logarithmic x-axis excel problem

[dairek]

Hey! I posted this yesterday, but wasn't able to find any solutions. I really need help with this!

I've been struggling with a graph I'm doing for a lab report.

I have two series, each with separate y-axes (linear) and both plotted on a logarithmic x-axis with the same x-axis values for both series. I expected the points on both series to line up vertically (since they have the same x-axis values) but as soon as I select a secondary y-axis for my second series, the second series markers cluster to the left as though they are no longer plotted on a logarithmic x-axis, and the two series no longer line up vertically.

I've tried making this graph in various orders, selecting both series together and separately, but I can't get this to work out. I have checked the values under the data series and made sure that they do in fact have the same cells selected for the x-coordinates.

Help me please!!

dairek

 

[pgc01]

the second series markers cluster to the left as though they are no longer plotted on a logarithmic x-axis, and the two series no longer line up vertically.

Hi Dairek

Did you check the format of the secondary X-axis?

After you send the second series to the secondary axis, do the following:
- Display the secondary X-axis
- go to the axis format and change it to logarithmic
- make sure both X-axes have the same maximum and minimum values
- hide the secondary X-axis again.

Remark1: I assumed you have a scatter chart

Remark2: always post your excel version (you can for ex. add this info to your board signature)

 

[dairek]

Hi PCG,

Thanks very much for your tips! I am running excel 2008 for mac, and I am indeed making a scatter chart. I hadn't realized that when I created a secondary y-axis that excel automatically selects secondary x-axis as well.

So I need to change the format of my secondary x-axis to match the primary axis. The problem I'm having now is that I can't figure out how to display the secondary x-axis - I've even tried moving the primary axis to see if it was underneath it, but I haven't been able to find it. Is there a toolbar that will allow me to do this?

Thank you very much,

dairek

 

[PA HS Teacher]

I'm not near Excel right now, and I don't work with secondary axes a ton. But in general I find that sometimes Excel treat the X Data as text...essentially 1 though N datapoints. That would be one possible explanation for bunching on the left (low numbers) on a logarhythmic plot. I would verify that the numbers in the X field actually are being treated as numbers.

For example you might multiply each data by 1. To do this enter 1 in an empty cell. copy, then do a paste special ..multiply on your X data.

 

[pgc01]

Hi PCG,

Thanks very much for your tips! I am running excel 2008 for mac, and I am indeed making a scatter chart. I hadn't realized that when I created a secondary y-axis that excel automatically selects secondary x-axis as well.

So I need to change the format of my secondary x-axis to match the primary axis. The problem I'm having now is that I can't figure out how to display the secondary x-axis - I've even tried moving the primary axis to see if it was underneath it, but I haven't been able to find it. Is there a toolbar that will allow me to do this?

Thank you very much,

dairek

Hi Dairek

I have excel for windows and so I'm not sure where it is in the mac. If I'm not mistaken the excel 2008 still uses the toobar based UI and so should be similar to older versions in windows.

If that's the case, this is how you'd do it in windows

- right-click on the chart
- choose Chart Options
- select the Axes tab on the form that pops up
- tick the Secondary Axis Value X-Axis

From then on the secondary axis is displayed on the chart and you can format it by right-clicking on it.

Hope this helps

 

[dairek]

Hi PCG,

I've been searching around on other forums and other excel 2008 mac users are having the same problem with secondary logarithmic x-axes - it looks like there is a glitch with the program.

Thank you very much for your suggestions!

- dairek