Isq

[emyanuthomas]

Hi,
I was trying to calculate I.sq, but noticed that I.sq reported by mr_egger() function and that manually calculated by the following code shows different results.
Q = sum((Bxse/Byse)^-2*(Bx/Byse-weighted.mean(Bx/Byse, w=(Bxse/Byse)^-2))^2)
Isq = max(0, (Q-(length(Bx)-1))/Q).

For eg. mr_egger(mr_input(bx = ldlc, bxse = ldlcse, by = chdlodds, byse = chdloddsse)) reports Isq = 91.9%
while the following code report Isq= 0.9647499
Bx=ldlc
Bxse = ldlcse
By = chdlodds
Byse = chdloddsse
Q = sum((Bxse/Byse)^-2*(Bx/Byse-weighted.mean(Bx/Byse, w=(Bxse/Byse)^-2))^2)
Isq = max(0, (Q-(length(Bx)-1))/Q)

Can you help me understand why this difference?

[gaborcsardi]

This is a read only mirror of CRAN, please see the DESCRIPTION file for the package authors.

[sb452]

It is because some of your bx are positive and others are negative. If you replace with:

Bx=abs(ldlc)
By = chdlodds*sign(ldlc)

then you should get Isq = 91.9%.