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 Bigaussian and Exponentially modified Gaussian		  New Topic  Reply to Topic
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hello901

3 Posts
Posted - 02/09/2018 :  1:37:28 PM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Hello,

I am currently fitting peaks and wanting to get a measure of asymmetry. I am fitting the peaks using either a Bigaussian or an Exponentially modified Gaussian and would like to be able to calculate the skewness of either fit so that they are comparable (ie: of the same sort of definition). Which definitions for the skewness of either distribution could I use such that the measurements are comparable.

arstern

USA
237 Posts
Posted - 02/09/2018 :  4:09:30 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,

There are multiple ways to go about this.

1. You can fit with the Peak Analyzer.
Within the Peak Properties Output tab select Peak Skew.

2. Once you fit with the nonlinear fit dialog. The output sheet will provide the x,y coordinates of the fit.

Next you can find the skewness of the fit, by selecting the x,y fit columns in your worksheet -> Select Statistics -> Descriptive Statistics -> Statistics on columns -> Open Dialog.

In the Quantities tab select Skewness. Select Ok.

Btw, you can as well compare fitting models with this feature:
https://www.originlab.com/doc/Origin-Help/PostFit-CompareFitFunc-Dialog

Thanks,
Aviel
OriginLab
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hello901

3 Posts
Posted - 02/09/2018 :  4:36:07 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Thank you very much for your reply and help :)
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hello901

3 Posts
Posted - 02/10/2018 :  07:37:08 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hello,

I do not know how to put error bars on the points using peak analyser. Where am I able to do this?
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arstern

USA
237 Posts
Posted - 02/12/2018 :  09:09:29 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,

To include the error with fitting: In the Fit Peaks (Pro) tab of the Peak Analyzer select Weight Method -> Instrumental and select the Data column with the error.



To include the error bars in the graph: You will need to first plot a graph with your data and error bars. Next activate the graph and open the Peak Analyzer dialog. The Graph with the Fitted Curve, data points, and error bars will be embedded in the FitPeaks worksheet tab.


Thanks,
Aviel
OriginLab
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