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Table 3 Absolute frequencies, outcome prevalences, exposure prevalences, crude and pooled prevalence ratio (PR) estimates, and relative confounding for the analysis of the original data using asthma as the outcome, maternal smoking as the risk factor and social class as confounder (situation 2 original).

From: Alternatives for logistic regression in cross-sectional studies: an empirical comparison of models that directly estimate the prevalence ratio

First stratum: High social class

 

Asthma

No

All

 
 

N

Prev.

N

N

Exp. prev. = 26.6%

Mother smokes

37

25.7%

107

144

PR = 1.19

No

86

21.6%

312

398

M-H weight = 22.85

All

123

22.7%

419

542

 

Second stratum: Low social class

 

Asthma

No

All

 
 

N

Prev.

N

N

Exp. prev. = 43.3%

Mother smokes

122

42.8%

163

285

PR = 1.24

No

129

34.6%

244

373

M-H weight = 55.87

All

251

38.1%

407

658

 

Combined strata: High and low social class

 

Asthma

 

No

All

Exp. prev. = 35.8%

 

N

Prev.

N

N

PR (crude) = 1.33

Mother smokes

159

37.1%

270

429

PR (M-H) = 1.22

No

215

27.9%

556

771

Confounding = -7.9%

All

374

31.2%

826

1200

P-value(het)*= 0.8

  1. * P-value for testing heterogeneity of the prevalence ratios across strata.