Table 3 

Summary Outcome Measures for Days of School Absence. 

Measure 
Effect Size 
Confidence Interval 
Effect Size Pvalue 
Homogeneity Test Pvalue 


SMD^{a} 

Fixedeffects 
0.14 
0.23, 0.04 
0.006 
0.61 
Randomeffects 
0.14 
0.23, 0.04 
0.006 
0.61 
IRD^{b} 

Fixedeffects MH 
0.15 
0.19, 0.11 
<0.001 
<0.001 
Randomeffects 
0.17 
0.25, 0.08 
<0.001 
<0.001 
IRR^{c} 

Fixedeffects MH 
0.86 
0.83, 0.90 
<0.001 
<0.001 
PR + study indicators 
0.86 
0.77, 0.97 
0.011 
<0.001 
PR  study indicators 
0.86 
0.75, 0.99 
0.044 
N/A 


^{a }SMD refers to standardized mean difference and was obtained using both fixed effects and random effects models. ^{b }IRD refers to the incidence rate difference, and was obtained using a MantelHaenszel procedure to estimate a fixedeffects model and an inversevariance method to estimate a randomeffects model. ^{c }IRR refers to the incidence rate ratio and was obtained using MantelHaenszel procedure to estimate a fixed effects model and Poisson regression models with HuberWhite sandwich estimators with and without study indicators which is equivalent to a randomeffects model. 

Guevara et al. BMC Medical Research Methodology 2004 4:17 doi:10.1186/14712288417 