 Analysis

• Status Assigned
• Percent Complete
0%
• Category Statistics
• Assigned To
• Operating System Windows
• Severity High
• Priority Very Low
• Reported Version 2.2
• Due in Version Undecided
• Due Date Undecided
• Private
Attached to Project: Analysis
Opened by Tom Nichols - 10.12.2013

FS#122 - significance tests for an adjusted odds ratio (options /t and /ex)

* EPIDATA ANALYSIS PROGRAM

logopen "H:\Teaching Courses\Outbreak Course\bugTN_06122013\bugTN_06122013.htm" /close /replace

cd "H:\Teaching Courses\Outbreak Course\bugTN_06122013"

set random simulations=10000

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* EpiData Analysis 2.2.1.171
* tables ill redsauce gheerchick /o /nt /nc /ex /t /obs
* Using 2.2.1.171: OR = 1.08 [95% CI 0.22 to 5.66]; p(M-H)=0.916; p(exact)=0.0414

* EpiData Analysis 2.2.2.182
tables ill redsauce gheerchick /o /nt /nc /ex /t /obs /oex
* Using 2.2.2.182: OR(Exact) = 1.08 [95% CI 0.22 to 5.66]; p(M-H)=0.046; p(exact)=0.0414
* Using 2.2.2.182: OR = 1.07 [95% CI 0.11 to 10.06]

* Epi Info for DOS v6.04d
* tables redsauce ill gheerchick
* Using Epi Info for DOS v6.04d: OR (MLE) = 1.08 [95% CI 0.22 to 5.66]; p(M-H uncorrected)=0.91644269; p(M-H corrected)=0.81105112

* Stata/SE 12.1 for Windows (32 bit) Revision 20 Mar 2013
* logit ill redsauce gheerchick
* P-value for coefficient of redsauce = 0.916

* The estimate is close to 1 and the confidence interval is wide, so a test for the adjusted OR being significantly different to 1 should have a p-value close to 1
* Both Epi Info for DOS and Stata give a p-value of 0.916
* So I have a lot of confidence in this being the correct p-value.

* EpiData Analysis (build 171)
* The chi-squared test statistic and the p-value for a M-H weighted odds ratio using the option /t is 0.01 and 0.916
* This p-value using the option /t appears to be correct.
* The p-value using the option /ex appears to be incorrect.
* The chi-squared test statistic and the p-value using the option /ex is 6.147 and 0.0414.
* If the test statistic is correct a comparison to a chi-squared distribution of 1 degree of freedom should give a p-value equal to 0.0132?
* Possibly the correct p-value should be calculated as 1-2*(0.0414) = 0.917?

* EpiData Analysis (build 182)
* The chi-squared test statistic and the p-value for a M-H weighted odds ratio using the option /t is 6.15 and 0.046
* This p-value using the option /t appears to be incorrect.
* The p-value using the option /ex appears to be incorrect.
* The chi-squared test statistic and p-value using the option /ex is 6.147 and 0.0414.
* If the test statistic is correct a comparison to a chi-squared distribution of 1 degree of freedom should give a p-value equal to 0.0132?
* Possibly the correct p-value should be calculated as 1-2*(0.0414) = 0.917?

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