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MustangoO
5 Posts |
 Posted - 05/17/2023 : 11:27:08 AM
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Hello! I have questions about the normal distribution (lognormal). I have a data distribution.
1. Using the command - select column - plot - histogram and then change Bin Size (5), I get a histogram in the coordinates Count-my data. I also turn on the distribution (double-click on the graph - distribution - curve type - lognormal).
2. Then I highlight the column with the data, Statistics - Descriptive Statistics - Frequency Counts - change number of bins (5) and
create standart table with Bin Center and Count. Then select column Bin Center and Count and plot the graph. This graph i copy on my histogram. In the end, on the graph i select points - analysis - Fitting - Non linear fitting - choose LogNormal Function and fit it.
As a result, I get the graph shown in the screenshot, where the red curve is obtained through automatic construction in the histogram menu, and the blue curve is obtained through the analysis menu.
Question - why don't the curves match if Bin number, size, minimum and maximum is equal in each case.  |
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YimingChen
1649 Posts |
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MustangoO
5 Posts |
Posted - 05/17/2023 : 4:23:04 PM
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Thanks for the answer!
But i have a one more question.
I read this article (https://www.originlab.com/doc/Quick-Help/CurveFit-on-Histogram) and plot new histogram with different Distribution - normal, lognormal and Weibull. Then I decided to change the bin size, but the distribution curves have not changed and now they don't look right. How can I rearrange these curves to fit the histogram?
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MustangoO
5 Posts |
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YimingChen
1649 Posts |
Posted - 05/18/2023 : 09:10:48 AM
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The magnitude of the distribution curve should change with the bin size as it scales with npts * binSize. Which version of Origin are you using? I couldn't reproduce your issue on Origin 2023b.
James |
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MustangoO
5 Posts |
Posted - 05/18/2023 : 3:03:44 PM
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| I'm using OriginPro 2021 (9.8.0.200) |
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YimingChen
1649 Posts |
Posted - 05/18/2023 : 3:20:52 PM
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I see. The distribution curves on your graph are generated from the distribution fit tool. In this case, once the curves are created, they will not change with the histogram bin size.
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MustangoO
5 Posts |
Posted - 05/19/2023 : 02:40:23 AM
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| Ah i see. Could you then help me to build the data distribution curve correctly so that it changes along with the change of the bin size? Or give a link to the section in Origin Help. |
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YimingChen
1649 Posts |
Posted - 05/19/2023 : 08:45:03 AM
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You could use menu Plot->Statistical->Histogram to make the plot. Then double-click on the plot. In the Plot Details dialog, go to Distribution tab, where you can add the distribution curve. The added curve should auto-rescale with the bin size.
James |
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Topic |
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Histogram analysis