Beckman Coulter User Forums

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When using an information plot, the default display for say median statistics, is two decimal places. If the "median" stat on the dotplot is calculated to be 0.41, it is shown on the Information plot as 0.41.

However, when the dotplot stat is less than 0.10 eg 0.04, it is displayed on the Information plot as 0.10 ie rounded up. Is there anyway I can get the Information plot to display the dotplot stat to the 2nd decimal place when it is < 0.10? ##### Share on other sites

Hello. In your information plot, when you click on the value field, you should see a formula that starts with "=MEDIAN(". Look at the third parameter to that function. Legal values are Logarithmic, Linear, and Logicle. For binned statistics such as median, this value needs to match the value used for your other statistic displays to guarantee that they match. Your plot seems to be Logicle, so your function should use that value. This parameter gets set when you choose Linear, Logarithmic, or Logicle from the sub-menu when picking a parameter for the information plot.

If this fixes your problem, you may wonder why this matters. Some statistics Kaluza calculates exactly, such as arithmetic mean. A numerically stable version of the standard technique is used and the value does not depend on how the data is presented. Other statistics like HPCV are defined in terms of a visual display, and so a histogram must be used to calculate them. Then there are statistics like median which are easily calculated from a histogram, but are too expensive to calculate exactly, so a histogram is used. Since you get different histograms for linear, logarithmic, and logicle displays, you also get different statistics when those histograms are used. These differences tend to be amplified when you have a small diffuse population, such as the one in your example.

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Thanks Ernie - that helps a lot! I know I'm being pedantic, but is a "new" histogram created to perform the calculation when a new Information plot is created independently from the media stats histogram created for the dot plot? If I increase the decimal places shown in fractional numbers fom 2 to 3, there is a slight difference in the two values shown. Interestingly the FL45- median in the Information plot is is 0.001 higher than the value shown in the dot plot, while the FL45+ Median is 0.001 lower. ##### Share on other sites

We have concluded our investigation. There is a design error. The information plot is using the default settings for the logicle transform. So the values will match if you do not adjust your logicle slider, but if you do these changes are not reflected to the information plot and the values will not match. I will ensure that this is included in our issue list.

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