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#1
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error bars when breaking the y-axis
Jon - I think this question is directed towards you. I have implemented a
version of your broken y-axis scheme. My data looks like the following: sample average avedev negative control 0.36252361 0.029793573 sample 1 3.265795907 2.878954305 sample 2 0.149275395 0.035304333 sample 3 73.57998574 2.237144009 sample 4 0.346937718 0.02837823 sample 5 4.636386221 0.089703534 sample 6 709.7039626 16.33742397 sample 7 1.157628293 0.667009325 negative control 0.494505996 0.051731733 RNase A 1pg/ml 1.604749215 0.106664119 As you can see, most of the sample are in the 0-5 range, but nos. 3 & 6 are way out. The question I have is how do I plot the avedev as error bars when I have broken the y-axis? I need to adjust these values to reflect the change I have made to the average series. I have the y-axis broken twice, with the sample #3 bar broken once and the sample #6 bar broken twice. I also did not use the method you use to calculate the midpoint of the bar for placement of the break; rather, I eyeballed it. |
#2
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This might ba a case where a log scale on the Y axis is better. You wouldn't need to
break the axis (twice!) and the error bars will show comparative deviations as a proportion of the average value. If you keep with the broken axis chart, you have three bands: 0 to 7, 70 to 76, and 690 to 730. Around 3/4 of the chart will have to be used for the uppermost band, which has only 1 point, while most of the points are crammed into the bottom 1/8 of the chart. This distorts the data worse than keeping the axis unbroken. On a log scale, in fact, points 1 and especially 7 show up as having remarkably wide avedev values, while all other points (except for point 2) have spreads smaller than the data markers in the chart. - Jon ------- Jon Peltier, Microsoft Excel MVP Peltier Technical Services Tutorials and Custom Solutions http://PeltierTech.com/ _______ Wazooli wrote: Jon - I think this question is directed towards you. I have implemented a version of your broken y-axis scheme. My data looks like the following: sample average avedev negative control 0.36252361 0.029793573 sample 1 3.265795907 2.878954305 sample 2 0.149275395 0.035304333 sample 3 73.57998574 2.237144009 sample 4 0.346937718 0.02837823 sample 5 4.636386221 0.089703534 sample 6 709.7039626 16.33742397 sample 7 1.157628293 0.667009325 negative control 0.494505996 0.051731733 RNase A 1pg/ml 1.604749215 0.106664119 As you can see, most of the sample are in the 0-5 range, but nos. 3 & 6 are way out. The question I have is how do I plot the avedev as error bars when I have broken the y-axis? I need to adjust these values to reflect the change I have made to the average series. I have the y-axis broken twice, with the sample #3 bar broken once and the sample #6 bar broken twice. I also did not use the method you use to calculate the midpoint of the bar for placement of the break; rather, I eyeballed it. |
#3
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I see what you're saying about changing the y-scale to log, as long as the
x-axis crosses at 0.1. This exercise was more for illustration purposes than actually trying to glean anything meaningful. i did figure out a way to scale the error bars to reflect the scaling of the data series however. Thanks for your help. "Jon Peltier" wrote: This might ba a case where a log scale on the Y axis is better. You wouldn't need to break the axis (twice!) and the error bars will show comparative deviations as a proportion of the average value. If you keep with the broken axis chart, you have three bands: 0 to 7, 70 to 76, and 690 to 730. Around 3/4 of the chart will have to be used for the uppermost band, which has only 1 point, while most of the points are crammed into the bottom 1/8 of the chart. This distorts the data worse than keeping the axis unbroken. On a log scale, in fact, points 1 and especially 7 show up as having remarkably wide avedev values, while all other points (except for point 2) have spreads smaller than the data markers in the chart. - Jon ------- Jon Peltier, Microsoft Excel MVP Peltier Technical Services Tutorials and Custom Solutions http://PeltierTech.com/ _______ Wazooli wrote: Jon - I think this question is directed towards you. I have implemented a version of your broken y-axis scheme. My data looks like the following: sample average avedev negative control 0.36252361 0.029793573 sample 1 3.265795907 2.878954305 sample 2 0.149275395 0.035304333 sample 3 73.57998574 2.237144009 sample 4 0.346937718 0.02837823 sample 5 4.636386221 0.089703534 sample 6 709.7039626 16.33742397 sample 7 1.157628293 0.667009325 negative control 0.494505996 0.051731733 RNase A 1pg/ml 1.604749215 0.106664119 As you can see, most of the sample are in the 0-5 range, but nos. 3 & 6 are way out. The question I have is how do I plot the avedev as error bars when I have broken the y-axis? I need to adjust these values to reflect the change I have made to the average series. I have the y-axis broken twice, with the sample #3 bar broken once and the sample #6 bar broken twice. I also did not use the method you use to calculate the midpoint of the bar for placement of the break; rather, I eyeballed it. |
#4
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P.S. - is there any way to adjust the error bars so the negative error bar is
the same size as th epositive error bar when using a log y-axis scale? Thanks again. "Jon Peltier" wrote: This might ba a case where a log scale on the Y axis is better. You wouldn't need to break the axis (twice!) and the error bars will show comparative deviations as a proportion of the average value. If you keep with the broken axis chart, you have three bands: 0 to 7, 70 to 76, and 690 to 730. Around 3/4 of the chart will have to be used for the uppermost band, which has only 1 point, while most of the points are crammed into the bottom 1/8 of the chart. This distorts the data worse than keeping the axis unbroken. On a log scale, in fact, points 1 and especially 7 show up as having remarkably wide avedev values, while all other points (except for point 2) have spreads smaller than the data markers in the chart. - Jon ------- Jon Peltier, Microsoft Excel MVP Peltier Technical Services Tutorials and Custom Solutions http://PeltierTech.com/ _______ Wazooli wrote: Jon - I think this question is directed towards you. I have implemented a version of your broken y-axis scheme. My data looks like the following: sample average avedev negative control 0.36252361 0.029793573 sample 1 3.265795907 2.878954305 sample 2 0.149275395 0.035304333 sample 3 73.57998574 2.237144009 sample 4 0.346937718 0.02837823 sample 5 4.636386221 0.089703534 sample 6 709.7039626 16.33742397 sample 7 1.157628293 0.667009325 negative control 0.494505996 0.051731733 RNase A 1pg/ml 1.604749215 0.106664119 As you can see, most of the sample are in the 0-5 range, but nos. 3 & 6 are way out. The question I have is how do I plot the avedev as error bars when I have broken the y-axis? I need to adjust these values to reflect the change I have made to the average series. I have the y-axis broken twice, with the sample #3 bar broken once and the sample #6 bar broken twice. I also did not use the method you use to calculate the midpoint of the bar for placement of the break; rather, I eyeballed it. |
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