Logarithmic error bar bug
When placing error bars on a column graph with a logarithmic Y axis, the
error bar is drawn as a large dark triangle connecting the last bar and it's neighbor. There is an error, something about negative and zero values in logarithmic scales, but there are no such values in the data. Is there a work-around for this? |
Logarithmic error bar bug
Hi,
Send me a copy of the chart and I will look at it when I get home tonight. -- Thanks, Shane Devenshire Microsoft Excel MVP "Jdoggrr" wrote: When placing error bars on a column graph with a logarithmic Y axis, the error bar is drawn as a large dark triangle connecting the last bar and it's neighbor. There is an error, something about negative and zero values in logarithmic scales, but there are no such values in the data. Is there a work-around for this? |
Logarithmic error bar bug
Check your Min and Max values to make sure the DIFFERENCE between the
plotted value and +/- error value is not zero (which can't be plotted on a log axis). In other words, the max or min error value cannot be the same as the plotted value for any data point. All the Best! |
Logarithmic error bar bug
I think I just figured this out. I was trying to create semilog scatter
plots (log scale on y axis) with custom error bars. My y-axis range was typically between 1 and 0.001. I was getting the same black triangle problem on both new Excel 2007 plots and even on old plots from 2003 that I opened in 2007. What I just tried was to add the error bars BEFORE applying the log scale on the y axis. IT worked! The error bars are scaled appropriately so that equal magnitude bars are drawn with positive bars shorter than negative ones. I also saved my test plot in Excel and reopened it. The correctly drawn error bars were preserved. I am able to copy these graphs to the clipboard, paste them into Word, save and reopen the Word file, and even edit the data from within Word. Also, If I change the magnitude of the error bar to greater than or equal the magnitude of the data point, I get a warning about plotting negative values on a log scale and a black triangle. I suspect that the original problem is an order of operations issue, so that Excel is checking to see if your proposed error bar length is too large BEFORE it adjusts the magnitude to match the log scale. I cannot believe it took me this long to figure this out, but I have been struggling with this for over a week while trying to finalize my dissertation. |
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