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*! Author: Ross Harris
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*! Date: 1 August 2008
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* Confidence interval for I-sq, to be run after metan
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version 8.0
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program i2ci
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local k = r(df)+1
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local q = r(het)
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if `q' > `k'{
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local selogH = 0.5 * ( ln(`q') - ln(`k'-1) ) / ( sqrt(2*`q') - sqrt(2*`k'-3) )
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}
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else{
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local selogH = sqrt( (1/(2*(`k'-2))) * (1- (1/(3*(`k'-2)^2))) )
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}
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local H = sqrt(`q'/(`k'-1))
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local Hlow = exp(ln(`H')-1.96*`selogH')
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local Hupp = exp(ln(`H')+1.96*`selogH')
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local I2 = string( r(i_sq) , "%5.1f")
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local I2low = string( max( 100* ( (`Hlow'^2-1) / `Hlow'^2 ) , 0) , "%5.1f")
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local I2upp = string( max( 100* ( (`Hupp'^2-1) / `Hupp'^2 ) , 0) , "%5.1f")
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di in ye "I-sq= `I2'%, 95% CI: `I2low'% to `I2upp'%"
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di in whi "CI based on Higgins & Thompson, Statist. Med. 2002; 21:1539–1558,
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di in whi "Appendix A2: Intervals based on the statistical significance of Q."
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end
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