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sterw
Netherlands
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 Posted - 01/22/2008 : 06:24:24 AM
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Origin Version Pro8 SR1
Operating System: Windows XP
I like the new feature in 8.0 that creates a results sheet with input data, fit parameters, statistics etc. It also shows a data plot with the fit and a residuals plot.
If a weighting method is used would it be possible to include error bars in those plots?
Wim
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larry_lan
China
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Posted - 01/23/2008 : 02:19:02 AM
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Hi Wim:
The error bars and weights are different. If you want to show error bars in the report worksheet, you'd better have a yErr column and fit from worksheet. (There is a bug when fit from graph, we will fix it soon). That is:
1. Say you have 3 columns, A, B, C. Right-click column C and Set As yErr.
2. Highlight these columns and bring up the fitting dialog.
By default, we will use the "Instrumental" weighting method, that is, w = 1/yErr^2. After fit, you will see error bars on report worksheet.
Thanks
Larry
OriginLab Technical Services |
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sterw
Netherlands
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Posted - 01/23/2008 : 03:11:39 AM
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You are right. I was fitting from the graph, not from the worksheet. That's why the error bars did not show up. Fitting from the worksheet shows error bars in the fit, but is it also possible to see the error bars in the residuals plot?
Thanks,
Wim |
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larry_lan
China
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Posted - 01/23/2008 : 04:47:21 AM
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Hi Wim:
Could you please tell me why you want to plot error bars on residual plots? I think it's not a "standard" way. Do you know any software implement this feature?
Whatever, you can create such plot by yourself: When you bringing up the fitter, select Same as Input Data in the X Data Type branch.
After fit, add one more column on the "FitNLCurves" worksheet (If you were using nonlinear fitting), beside the Residual values column, copy+paste the Error value to this column. Then set this column as yErr and create a scatter plot.
Thanks
Larry
OriginLab Technical Services |
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sterw
Netherlands
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Posted - 01/23/2008 : 08:03:30 AM
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In the same manner as a chisquared value (that by definition includes error bars) gives me more information about a fit than just the squared deviation the error bars in residual plots are for me visual aids to spot significant deviations from zero. I was just wondering if it could be implemented in the result sheet.
Thanks for pointing out how it can be realized in a different way. It works, by the way, also if for the X Data Type the standard Uniform Linear setting is chosen. That setting apparently only applies to the fit values. The residuals are always calculated at the data points.
I have limited experience with other related software. We used to work with Igor Pro, where it is not a standard feature as well(although relatively easy to implement).
Wim |
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results sheet in 8.0