[R] Draw a nomogram after glm

Komine momadou at yahoo.fr
Tue May 10 09:50:12 CEST 2011


Hi, 
I try always to do my nomogram. I change little my code in order to definite
the range of my linear predictor. 
But I do not succeed to have 0 until 1. I tried this code.   
library(rms)
d <- datadist(Fire)
options(datadist='d')
Fire$Ignition=c(0,1,by=0.1)
f<-lrm(Ignition~FMC+Charge,data=Fire)
print(f)
summary(f,FMC=c(0,506.40),Charge=c(45,646))
plot(nomogram(f, interact=list(FMC,Charge))) 

The result is: 

> print(f)

Logistic Regression Model

lrm(formula = Ignition ~ FMC + Charge, data = Fire)

                     Model Likelihood     Discrimination    Rank Discrim.    
                        Ratio Test            Indexes          Indexes       

Obs           231    LR chi2      0.04    R2       0.000    C       0.501    
 0             77    d.f.            2    g        0.026    Dxy     0.002    
 0.1           77    Pr(> chi2) 0.9796    gr       1.026    gamma   0.003    
 1             77                         gp       0.006    tau-a   0.002    
max |deriv| 7e-13                         Brier    0.222                     


       Coef    S.E.   Wald Z Pr(>|Z|)
y>=0.1  0.6832 0.3018  2.26  0.0236  
y>=1   -0.7033 0.3020 -2.33  0.0199  
FMC     0.0002 0.0011  0.18  0.8601  
Charge -0.0001 0.0009 -0.07  0.9424  


> summary(f,FMC=c(0,506.40),Charge=c(45,646)) 
             Effects              Response : Ignition 

 Factor      Low High  Diff. Effect S.E. Lower 0.95 Upper 0.95
 FMC          0  506.4 506.4  0.10  0.58 -1.04      1.24      
  Odds Ratio  0  506.4 506.4  1.11    NA  0.36      3.45      
 Charge      45  646.0 601.0 -0.04  0.55 -1.11      1.03      
  Odds Ratio 45  646.0 601.0  0.96    NA  0.33      2.81      
> plot(nomogram(f, interact=list(FMC,Charge)))   
    http://r.789695.n4.nabble.com/file/n3511218/nomogram_2.jpeg 
Please can I do to have linear predictor between 0 to 1. 
Thanks very much for your Help
Komine

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