Write multiple IF statements in more clever way+ connect it to macro var

[Ronein]

Hello

In my raw data I have information of failure for each customer.(Each customer has one row).

For each customer there is a potential follow up of 15 months and we check If he/she touch failure at this period.

Some of the customers didn't complete the full 15 months of following up periods.

My question:

I need to write 15 IF statements.

What is the better way to do it?(More clever way)?

It also might happen in the future that I need to run it on following up of different period...so maybe it is better to add a macro var  

%let k=15;

that define the potential follow up period and then the IF statements will be adjusted automatic.

Another question, Do you think that in this case I need to use "ELSE IF" statements or "IF"?(I know that result will be same but I want to ask what do you think)

IF   No_Months_Exposed=15   then  Ind_Touch_Failure=MAX(OF grade1-grade15);							
ELSE IF   No_Months_Exposed=14   then  Ind_Touch_Failure=MAX(OF grade2-grade15);							
ELSE IF   No_Months_Exposed=13   then  Ind_Touch_Failure=MAX(OF grade3-grade15);							
ELSE IF   No_Months_Exposed=12  then  Ind_Touch_Failure=MAX(OF grade4-grade15);							
ELSE IF   No_Months_Exposed=11  then  Ind_Touch_Failure=MAX(OF grade5-grade15);							
ELSE IF   No_Months_Exposed=10  then  Ind_Touch_Failure=MAX(OF grade6-grade15);							
ELSE IF   No_Months_Exposed=9   then  Ind_Touch_Failure=MAX(OF grade7-grade15);							
ELSE IF   No_Months_Exposed=8   then  Ind_Touch_Failure=MAX(OF grade8-grade15);							
ELSE IF   No_Months_Exposed=7   then  Ind_Touch_Failure=MAX(OF grade9-grade15);							
ELSE IF   No_Months_Exposed=6   then  Ind_Touch_Failure=MAX(OF grade10-grade15);							
ELSE IF   No_Months_Exposed=5   then  Ind_Touch_Failure=MAX(OF grade11-grade15);							
ELSE IF   No_Months_Exposed=4   then  Ind_Touch_Failure=MAX(OF grade12-grade15);							
ELSE IF   No_Months_Exposed=3   then  Ind_Touch_Failure=MAX(OF grade13-grade15);							
ELSE IF   No_Months_Exposed=2   then  Ind_Touch_Failure=MAX(OF grade14-grade15);							
ELSE IF   No_Months_Exposed=1   then  Ind_Touch_Failure=MAX(OF grade15-grade15);							

[novinosrin]

%macro t;
 %do i=15 %to 1 %by -1;
  %let t= %eval(15-&i+1);
  %if &i<15 %then  else  ;
  if No_Months_Exposed=&i then Ind_Touch_Failure=MAX(OF grade&t-grade15);
 %end;
%mend t;



options mprint;
/*Call the macro*/
data want;
 set have;
 %t;
run;

117  options mprint;
118  /*Call the macro*/
119  data want;
120   set have;
121   %t;
MPRINT(T):   if No_Months_Exposed=15 then Ind_Touch_Failure=MAX(OF grade1-grade15);
MPRINT(T):   else if No_Months_Exposed=14 then Ind_Touch_Failure=MAX(OF grade2-grade15);
MPRINT(T):   else if No_Months_Exposed=13 then Ind_Touch_Failure=MAX(OF grade3-grade15);
MPRINT(T):   else if No_Months_Exposed=12 then Ind_Touch_Failure=MAX(OF grade4-grade15);
MPRINT(T):   else if No_Months_Exposed=11 then Ind_Touch_Failure=MAX(OF grade5-grade15);
MPRINT(T):   else if No_Months_Exposed=10 then Ind_Touch_Failure=MAX(OF grade6-grade15);
MPRINT(T):   else if No_Months_Exposed=9 then Ind_Touch_Failure=MAX(OF grade7-grade15);
MPRINT(T):   else if No_Months_Exposed=8 then Ind_Touch_Failure=MAX(OF grade8-grade15);
MPRINT(T):   else if No_Months_Exposed=7 then Ind_Touch_Failure=MAX(OF grade9-grade15);
MPRINT(T):   else if No_Months_Exposed=6 then Ind_Touch_Failure=MAX(OF grade10-grade15);
MPRINT(T):   else if No_Months_Exposed=5 then Ind_Touch_Failure=MAX(OF grade11-grade15);
MPRINT(T):   else if No_Months_Exposed=4 then Ind_Touch_Failure=MAX(OF grade12-grade15);
MPRINT(T):   else if No_Months_Exposed=3 then Ind_Touch_Failure=MAX(OF grade13-grade15);
MPRINT(T):   else if No_Months_Exposed=2 then Ind_Touch_Failure=MAX(OF grade14-grade15);
MPRINT(T):   else if No_Months_Exposed=1 then Ind_Touch_Failure=MAX(OF grade15-grade15);
122  run;

[Tom]

Why not use an array to eliminate the need for the wallpaper code and hence any macro logic to generate the wallpaper code.

array grade [15];
Ind_Touch_Failure=.;
do index=(15-No_Months_Exposed+1) to 15 ;
  Ind_Touch_Failure=max(Ind_Touch_Failure,grade[index]);
end;

[SASKiwi]

@Tom - Love that term wallpaper code! Must add that to my lexicon.