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 log normal distribution
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aiva18

Canada
5 Posts

Posted - 02/09/2009 :  3:29:31 PM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Origin Ver.8 and Service Release (Select Help-->About Origin):
Operating System: WIndows Xp
Hi,
I have a question regarding statistics on colums.
The distribution is known that is a log normal distribution. However, the columns consist of bins, and some bins are missing. i will insert the image to illiustrate it. Origin sometimes ignores the bins that are higher and only does the fitting through the peak. The fit in black line is done in excel using macro and red line Origin fit. How this fitting in Origin is actually done ?

Deanna

China
Posts

Posted - 02/10/2009 :  04:47:49 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,

I am not sure how the Excel macro work. But it looks like that you want to use weighted fitting because you have error bars on the columns and the fitted result of Excel seems to include weights. But this is only my guess. Please send me your data including the Excel result and probably the excel macro so that I can verify my guess. For sending files, please follow the below instructions:
http://www.originlab.com/index.aspx?s=1&lm=123&pid=752

As for how Origin performs curve fitting, you can see here:
http://www.originlab.com/www/helponline/Origin8/en/origin.htm#regression_and_curve_fitting/interpreting_regression_results.htm


Deanna
OriginLab Technical Services
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aiva18

Canada
5 Posts

Posted - 02/23/2009 :  5:09:51 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,
I dont have the excel macro. I have email the data to info@originlab.com, because I had difficulty in uploading the data file to your website.
I hope you can try fitting the curve into this data. y has to be equal 0.
Sincerely,
Daiva
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Deanna

China
Posts

Posted - 02/25/2009 :  04:52:32 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Yes, this is indeed a weighting issue. When Direct Weighting is used, Origin can generate a fitted curve very closed to Excel's. If you are interested in the weighting methods available in Origin 8's non-linear curve fitting tool, please read:
http://www.originlab.com/www/helponline/Origin8/en/regression_and_curve_fitting/fitting_with_errors_and_weighting.htm

Deanna
OriginLab Technical Services
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aiva18

Canada
5 Posts

Posted - 03/01/2009 :  12:21:25 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Would you know how in Origin 8 version, is possible to sort the data into different size bins, in order to plot histogram. I used to sort all data in the same size bins. Using Frequency count in Statistics Menu bar, program allows to choose Computational control (Min and Max) and Increment (bin size). Now i require lets say, from 2 till 40 sort into 2 size bins, and after 40 sort into 5 size bins. How can I do that ?

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aiva18

Canada
5 Posts

Posted - 10/15/2009 :  5:21:11 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,
I have a question about log normal fit parameters. In a graph, A is an amplitude, but y axis is in percent. After fit A=166. What does this number is calculated and what it means ?

Thank you,
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easwar

USA
1965 Posts

Posted - 10/16/2009 :  10:19:52 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
quote:
Originally posted by aiva18

Would you know how in Origin 8 version, is possible to sort the data into different size bins, in order to plot histogram. I used to sort all data in the same size bins. Using Frequency count in Statistics Menu bar, program allows to choose Computational control (Min and Max) and Increment (bin size). Now i require lets say, from 2 till 40 sort into 2 size bins, and after 40 sort into 5 size bins. How can I do that ?



Hello,

This feature of custom binning is being added to the upcoming version 8.1
It will be accessible from script, where user can specify a column that contains the custom bin end values to be used for the binning.

Easwar
OriginLab
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