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EpiData Analysis V2.2.2.182 10/12/2013 17:41

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

. read "H:\Teaching Courses\Outbreak Course\bugTN_06122013\wedd" /close

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File name :H:\Teaching Courses\Outbreak Course\bugTN_06122013\wedd.REC
double food outbreak
Fields: 3 Total records: 134 Included: 134

. set random simulations=10000

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

ill (diarrhoea or abdominal pain) by Red seasoning sauce adjusted for Jeera chicken
N = 130NOR(95% CI)pexactChi2Dfp        1
1  a
0  c
0
  b
  d
ORExact(95% CI)
Crude130 3.42(1.10-10.60) 0.0374 4.9201 0.027 24
65
4
37
3.39(1.05-14.47)
Adjusted130 1.07(0.11-10.06) 0.0414 6.151 0.046 1.08(0.22-5.66)

 

 Jeera chicken: 080 0.20(0.02-1.84) 0.1763 2.444*1 0.118 1
42
4
33
0.20(0.00-2.15)
 Jeera chicken: 150-inf.( inf- inf) 0.1147 3.704*1 0.054 23
23
0
4
-inf.(0.59- inf)
Summary Estimates
Total 2 strata. 2 informative & 0 non-informative.
 Exposure: Red seasoning sauce = 1
 Outcome: ill (diarrhoea or abdominal pain) = 1
*: Small Expected Numbers, use Pexact /ex

Exact Monte Carlo tests: 10000 simulations
  Chi2 = 6.147 df(1) p=0.0414

* 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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