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Posted 06-21-2018 04:03 AM
(2750 views)

Hello community,

I really request for assistance. I want to calculate the Nam-D'Agostino Test which is an extension of Hosmer Lemeshow test adapted to survival data.

Attached to this message is the formula I am supposed to use to calculate this statistic but I dont know how to write the code and I have not come across any code on internet for almost 3 month of searching. Community , I request for your assistance.

Thank you in advance.

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Thank you Mr. Rick for the article about calibration plots. I have followed it and was able to get the concept for obtaining calibration plot using the Phreg procedure. However, I would be glad if am also assisted to find a way to calculating the associated Chi Square and P values using this formula modified by Nam-D'Agostino.

There are other people who have tried to search for the same calculating on this forum but they had no replies about this calculation, so i failed to get any ideas about how the coding should be done.

I will be glad to receive more additional assistance from you and other community advisors.

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Hello Rick,

This is what I have tried out so far.

/* USING PHREG PROCEDURE TO SAVE PREDICTED PROBABILITIES FROM THE COX MODEL */

Proc phreg data=Stone1.Development;

class SEX(ref='2') AGE (ref='1') SMOKING(ref='1') DRINKING(ref='1') CHOLESTEROL(ref='1') TRIGLYCERIDES(ref='1') OBESITY(ref='1') GLUCOSE(ref='1') SBP(ref='1');

model Years * Censor (0)=Sex AGE SMOKING DRINKING CHOLESTEROL TRIGLYCERIDES OBESITY GLUCOSE SBP/ rl;

output out=OutData Survival=PredProb; /* Saving predicted probabilities in data set */

run;

/* IDENTIFICATION OF DECILES OF PREDICTED PROBABILITIES*/

Proc rank data=OutData out=Decile groups=10;

var PredProb;

ranks Decile;

run;

/* COMPUTATION OF THE MEAN PREDICTED PROBABILITIES AND THEIR CONFIDENCE INTERVALS*/

proc means data=Decile noprint;

class Decile;

types Decile;

var PredProb;

output out=MeanDecileOut mean= PredProbMean

lclm=PredProbLower uclm=PredProbUpper;

run;

*/Desription of Variables in my data desription*/

*/Years=Varibale for time ot event or follow up time for each indivividual in the cohort*/

*/Censor=Censoring variable with censor(0) representing censored participant and Censor(1) representing participants who expereinced the outcome of interest*/

*/PredProb is the variable containing individual Survival probabilties that I obtained from the a multivariable Cox proportional Hazards model as seen above/*

*/Desription of Variables in Nam-D'Agostino Test formula*/

Below is the formula to calculate the statistics for each decile.

[KMg(t)- p(t)g]Squared *ng /p(t)g(1-p(t)g)

Then summation for all deciles to get the overal statistcis for the model.

Where

*/KMg(t) represents the failure probability in g-th decile at time t*/

*/ p(t)g is the mean predicted probability of failure for subjects in g-th decile using any survival modelling technique [ I am using Cox model]/*

*/ng is number of observations in a group g/*

Thank you RICK for your continued assistance. Will be glad to receive your assistance again.

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