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sharon19
Joined: 09 Apr 2010 Posts: 21
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Posted: Mon Jun 21, 2010 1:41 pm Post subject: what can I do when my logistic reg model has poor calibratio |
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For medicine and AUC >700 is considered good, so I am okay. I have AUC of 760
BUT my H-L test is p=0
I have read about using clustering as a way to increase calibration, but the paper was complex. I read somewhere that the calibration does not matter. I want to write up a paper so I do not know what to do.
My equation is simple
Resuscitation Code Status = AGE + GENDER + SAPS SCORE
Besides making AGE binary, which I have had trouble doing, I do not know what to do.
Ultimately I am interested in the model to derive Odds Ratios to determine ageism or gender bias
Many thanks.
Sharon
Oh, and though I do not think this will work, if AGE (continuous) does not have an interaction term, do I have to repeat the interaction study if I change AGE to binary? |
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alethephant
Joined: 06 Sep 2006 Posts: 200 Location: Virginia Beach
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Posted: Mon Jun 21, 2010 3:32 pm Post subject: What can I do when my logistic reg model |
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1. What is "AUC"? Is this "Area Under Curve" in a ROC plot? If so, does "760" mean 0.76?
2. What is "H-L"? Is this the Hosmer-Lemeshow test? If so, you need to describe more about how you carried it out and how many classes you used and how many data you have.
3. AGE is a complicated variable, and you don't describe what range and ages you have, and how you expect them to relate to your RCS response.
4. What are your "clusters"? Are these institutions you sampled at?
Etc. |
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sharon19
Joined: 09 Apr 2010 Posts: 21
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Posted: Mon Jun 21, 2010 3:37 pm Post subject: |
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Yes to numbers one and two, sorry for my abbreviations.
Age ranges from 15 - 100 exactly (due to de-identification). The mean is around 65 years
I have approximately 17,000 subjects.
I do not have any clusters, it was just a thought. All the data comes from one hospital, but it does come from different ICUs (about 7 of them)
Thank you |
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alethephant
Joined: 06 Sep 2006 Posts: 200 Location: Virginia Beach
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Posted: Tue Jun 22, 2010 9:41 am Post subject: What can I do when my logistic reg model |
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The 7 ICUs are probably clusters (correlation among subjects in same ICU).
You have a wide range of AGE, so if you are going to categorize it, you should use more than 2 categories. Perhaps 4 or more to capture the association.
As to your question of "calibration", which I presume means "goodness of fit" or "stability of fit", validation is a good idea if you have a lot of data. |
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sharon19
Joined: 09 Apr 2010 Posts: 21
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Posted: Tue Jun 22, 2010 2:38 pm Post subject: |
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what do you mean by validation? Yes I mean goodness of fit.
Thank you,
Sharon  |
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alethephant
Joined: 06 Sep 2006 Posts: 200 Location: Virginia Beach
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Posted: Tue Jun 22, 2010 6:45 pm Post subject: What can I do when my logistic reg model |
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Validation usually means verifying stability of a model by holding out portions of data and seeing if the model remains essentially the same when fit on different portions.
This can be a dichotomy, such as 70% for training and 30% for validation, or a trichotomy of 50% for training, 30% for design level validation and 20% for final independent validation of the selected model.
Or it can be a more systematic approach, such as jackknifing, bootstrapping or other techniques with a sampling component. |
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sharon19
Joined: 09 Apr 2010 Posts: 21
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Posted: Tue Jun 22, 2010 8:42 pm Post subject: |
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| thank you very much. I have used validation for classification, but I did not realize it meant the same thing here. Thank you |
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LeeRain
Joined: 25 Jun 2010 Posts: 3
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Posted: Fri Jun 25, 2010 2:38 am Post subject: |
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You have a wide range of AGE, so if you are going to categorize it, you should use more than 2 categories. Perhaps 4 or more to capture the association.  _________________ import trade lead
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Sam13
Joined: 31 Jul 2010 Posts: 1
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Posted: Sat Jul 31, 2010 1:17 am Post subject: |
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Thank you everybody...
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zihad36
Joined: 18 Aug 2010 Posts: 1
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Posted: Wed Aug 18, 2010 1:30 pm Post subject: |
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I have approximately 17,000 subjects.
I do not have any clusters, it was just a thought. All the data comes from one hospital, but it does come from different ICUs (about 7 of them)
online bingo |
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raat475
Joined: 28 Aug 2010 Posts: 1
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Posted: Sat Aug 28, 2010 4:02 pm Post subject: |
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I read somewhere that the calibration does not matter. I want to write up a paper so I do not know what to do.
My equation is simple
Resuscitation Code Status = AGE + GENDER + SAPS SCORE
Besides making AGE binary, which I have had trouble doing, I do not know what to do.
retouching |
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zia111
Joined: 04 Sep 2010 Posts: 1
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Posted: Sat Sep 04, 2010 6:30 pm Post subject: |
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I have read about using clustering as a way to increase calibration, but the paper was complex. I read somewhere that the calibration does not matter. I want to write up a paper so I do not know what to do.
no deposit bingo |
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