sas 如何计算概率的一般加法公式

shiyiming

对于n个事件的加法公式在这个页面上不太好输入，写出
两个事件的概率加法公式 P(AuB)=P(A)+P(B)-P(AB)，
现在问题是，有一个变量，它有n个观测值，其中每个观测值都
代表相应事件发生的概率，想求出各事件和的概率，该如何计算呢？
sas中有没有相应的程序呢？请各位帮助，谢谢！

shiyiming

any event should be indepedent?

shiyiming

assume any p(XY) =P(X)P(Y).
and set all prob names as p1, p2, p3, ...
I propose a code for that:
[code:piriddtc]%macro break;
   %let nL =%sysfunc(countw(&String));
   %let LastW =%scan(&String, &nL);
   %let String =%sysfunc(tranwrd(&String, &LastW,%str() ));
   ((&String) *(1-&LastW) +&LastW)
%mend;

option mprint mlogic symbolgen;
%macro LastW(n =); %global formula;
   %let n1 =%eval(&n -1); %let formula =; %let String=;
   %local i;
   %do i =1 %to &n1;
      %let formula =&formula p&i;
   %end;
   %let formula =(&formula)*(1-p&n) +p&n;
   %do i =1 %to &n;
      %let String =&String p&i;
   %end;
   %do i=1 %to &n1;
      %let formula =%sysfunc(tranwrd(&formula, &String,%break));
   %end ;
%mend LastW;


data _null_;
   array p[100] (100*0.01);
   %LastW(n =2)
   ;
   rr0 =&formula;put rr0=;
   %LastW(n =3)
   ;
   rr0 =&formula;put rr0=;
   %LastW(n =10)
   ;
   rr0 =&formula;put rr0=;

   %LastW(n =100)
   ;
   rr0 =&formula;put rr0=;
run;[/code:piriddtc]
jingju

shiyiming

[quote="jingju11":1i6ffk5o]assume any p(XY) =P(X)P(Y).
and set all prob names as p1, p2, p3, ...
I propose a code for that:
[code:1i6ffk5o]%macro break;
   %let nL =%sysfunc(countw(&String));
   %let LastW =%scan(&String, &nL);
   %let String =%sysfunc(tranwrd(&String, &LastW,%str() ));
   ((&String) *(1-&LastW) +&LastW)
%mend;

option mprint mlogic symbolgen;
%macro LastW(n =); %global formula;
   %let n1 =%eval(&n -1); %let formula =; %let String=;
   %local i;
   %do i =1 %to &n1;
      %let formula =&formula p&i;
   %end;
   %let formula =(&formula)*(1-p&n) +p&n;
   %do i =1 %to &n;
      %let String =&String p&i;
   %end;
   %do i=1 %to &n1;
      %let formula =%sysfunc(tranwrd(&formula, &String,%break));
   %end ;
%mend LastW;


data _null_;
   array p[100] (100*0.01);
   %LastW(n =2)
   ;
   rr0 =&formula;put rr0=;
   %LastW(n =3)
   ;
   rr0 =&formula;put rr0=;
   %LastW(n =10)
   ;
   rr0 =&formula;put rr0=;

   %LastW(n =100)
   ;
   rr0 =&formula;put rr0=;
run;[/code:1i6ffk5o]
jingju[/quote:1i6ffk5o]

这个程序太强大了，很多地方看不懂。多时能像jingju这样就好了。