# Excel xy chart with unequal x values in series

I am a senior doing a science fair project on the efficiency of fuels. For each fuel I tested, I have a time series of temperature. I want to plot these into an excel xy chart, how do I plot them if the constants (time) are not the same for each set of data?

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What program are you using to make the plots? –  charles.y.zheng Mar 18 '11 at 15:44
Try to be more concise, like this. Otherwise you have a small chance that someone would try to decipher the question, and thus a little chance for an answer. –  mbq Mar 18 '11 at 16:09

Use a Scatter Plot where the horizontal axis is time. Below is a screenshot of an Excel sheet where two temperatures are shown. Temp 1 starts at 9:00:00 AM and increments by 1 minute and 26 seconds. Temp 2 starts at 9:30:00 AM and increments by 2 minutes and 53 seconds. They are both plotted in the graph.

As shown in the plot, the blue Temp 1 has been "selected" in the graph and the corresponding graph formula is:

=SERIES(Sheet1!$B$1,Sheet1!$A$2:$A$27,Sheet1!$B$2:$B$27,1)

When I select Temp 2, the corresponding graph formula is:

=SERIES(Sheet1!$E$1,Sheet1!$D$2:$D$27,Sheet1!$E$2:$E$27,2)

Both Temp 1 and Temp 2 uses the same x-axis and y-axis.

There is a second way to do this where the blue series has its own x-axis and y-axis, and the red series has a different x-axis and y-axis. However, I wouldn't recommend this scheme because it is typically too confusing for others to interpret the results. It requires that you assign one (or more) of the lines to a secondary y-axis and then a secondary x-axis. Here are the steps:

1) Right click on the series that you want to assign to the secondary axes. Select "Format Data Series". Under "Series Options" select "Secondary Axis". That will assign the selected series to a secondary y-axis.

2) With the series still selected, go to the "Chart Tools" "Layout" "Axes" selection on the ribbon. Click "Secondary Horizontal Axis" and pick whatever options you want. That will assign the selected series to a secondary x-axis.

Below is an example. I purposely changed the color of the text of the lower x-axis and the left y-axis to blue to signify that these are the axes to use for the blue series.

I changed the color of the text of the upper x-axis and the right y-axis to red to signify their use for the red series.

Notice that the two y-axes have different scales. The blue y-axis runs from 0 to 90, while the red y-axis runs from 0 to 100.

Notice also that I set both x-axis to start, stop, and increment at the same values. If you set the increment of the two x-axes to two different values, this graph can be even more confusing.

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