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标题: sas 如何计算概率的一般加法公式 [打印本页]

作者: shiyiming 时间: 2012-6-14 23:58
标题: sas 如何计算概率的一般加法公式
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！

作者: shiyiming 时间: 2012-6-19 05:46
标题: Re: sas 如何计算概率的一般加法公式
any event should be indepedent?

作者: shiyiming 时间: 2012-6-19 07:32
标题: Re: sas 如何计算概率的一般加法公式
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

作者: shiyiming 时间: 2012-7-24 08:47
标题: Re: sas 如何计算概率的一般加法公式
[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。

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