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helenachui
4 Posts |
 Posted - 09/29/2011 : 03:10:02 AM
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Origin Ver. 8.5 and Service Release 1:
Operating System: Vista 64 bit
Dear Sir/Madam,
I have some questions about ROC curve.
1. Is there a way that I can label the thresholds on the ROC curve, such that I can show the value of the best cutoff, i.e. the point having the best balance of specificity and sensitivity?
I want something like the "best thresholds" function in the R package pROC. The problem I have with pROC is that, the thresholds used are not integers. pROC is using thresholds such as 1.5, 3.5... etc. So, here's my second question.
2. How do I obtain the thresholds used to create the plot in Origin? And can I set the thresholds to be integers?
Hope someone can help.
Many thanks,
Helena
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helenachui
4 Posts |
Posted - 09/29/2011 : 03:39:59 AM
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Hi,
I have one more question about ROC in Origin. I used the same data and plotted ROC in R, using packages pROC, ROCR, and verification. All packages show me similar plots. The test does pretty good to predict diagnostic states.
However, when I use the same data in Origin, the test works way worse than the reference line. And to obtain a plot that looks like the plots I got in R, I have to set the state value = 0, instead of 1. Is this a bug in Origin?
Thanks,
Helena |
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Echo_Chu
China
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Posted - 09/30/2011 : 03:06:26 AM
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Hi, Helena
I am sorry that Origin 8.5 only compute the thresholds internally. So they are not available in Origin 8.5 yet. Our coming version, Origin 8.6 is improved to have threshod values reported to result.
In Origin 8.5, the state value you should specified is negative state value, which might be different from R. However, in Origin 8.6, we have improved it.
Thanks
Echo |
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___@___
USA
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Posted - 11/01/2012 : 6:30:02 PM
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| I am right now looking for this feature in Origin 8.6 Pro but can't find it. Is it already included? How to calculate the optimal threshold? |
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___@___
USA
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Echo_Chu
China
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Posted - 11/02/2012 : 02:29:28 AM
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Hi, Dan
In Origin 8.6, the threshold are output in the ROCValue1 sheet. You can look at the Cut Off column to find the values. They are computed from interpolation of the original data whose state are positive.
Thanks
Echo
quote:
Originally posted by ___@___
I am right now looking for this feature in Origin 8.6 Pro but can't find it. Is it already included? How to calculate the optimal threshold?
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___@___
USA
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Posted - 11/02/2012 : 04:18:19 AM
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| Thank you Echo, but these are only the cut off values, and not the cost functions. So how do I construct the cost function to find the optimal cut off value in Origin? |
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ROC thresholds