Dear R-ers,
We are doing prediction of risk for aortic aneurysm in screened
subjects based on different riskfactors. When we do the prediction on
the linklevel and transform the prediction and the limits of the 95%-
confidence intervall (with exponentiation and then transformation from
odds to probability) we get asymmetric intervalls which seem
reasonable. When we use prediction on the responselevel (which is be
on the probability level) the intervalls are completely symmetric. The
figures are also different. Is something wrong with the prediction or
with my use of the glm program?
Any help much appreciated!
Sincerely yours
Fredrik Lundgren
This is for an individual with certain riskfactors
Formation of confidence interval with linklevel (prob transforms from
odds to probability) fit = -4.7513497 and se.fit = 0.2474956
point value lower limit
upper limit
prob(exp(-4.7513497)) prob(exp(-4.7513497-1.96*0.2474956))
prob(exp(-4.7513497+1.96*0.2474956))
Formation of confidence interval with responselevel fit = 0.008566015
and se.fit= 0.002101891
point value lower limit
upper limit
0.008566015 p0.008566015-1.96*0.002101891 0.008566015+1.96*0.002101891
########################
Fredrik Lundgren
fredrik.bg.lundg...@gmail.com
Engelbrektsgatan 31
582 21 Linköping
tel 013 - 47 30 117
mob 0706 - 86 39 29
Sommarhus: Ljungnäs 158
380 30 Rockneby
0480 - 650 98
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