%let intercept = 2.197; 
%let betaL = -0.2285; 
%let betaQ = 0.00254; 
data crash; 
do age = 15 to 85 by 0.5; 
Logit = &intercept + &betaL*age + &betaQ*age*age; 
p = exp(Logit)/(exp(Logit)+1); 
output; end; 
proc gplot; plot Logit*age/vref=0; 
plot P*age/vref=0.5; 
run; 

** Make a scatterplot matrix in INSIGHT
   Y=(L p age)  X=(age L)
******; 



/*** Optional: Given the age of minimum probability and the
max and min probabilities, compute the quadratic 
equation for generating the  logit  ************; 
Data coeff; 
%let min_p_age = 45; 
%let maxp=.9; 
%let minp = .05; 
Data a; 
 do age = 18 to 90 by 10; 
 Lmin = log(&minp/(1-&minp));
 Lmax = log(&maxp/(1-&maxp)); 
 Logit = Lmin+(Lmax-Lmin)*((age-&min_p_age)/(90-&min_p_age))**2; 
 p = exp(Logit)/(1+exp(Logit)); 
 output; end; 
 proc gplot; plot p*age; 
 proc glm; model Logit = age age*age; 
 run; 
 * */