Hays Files

*****************************************************************************;
* *;
* HAYSPOWEM.SAS: Hays' power macro written in SAS. *;
*                                  *;
* Original program written in BASIC by Ron Hays, 1996. *;
* see: *;
* http://www.gim.med.ucla.edu/FacultyPages/Hays/util.htm (hayspowe.bas) *;
*                   *;
*                   *;
* This program, HAYSPOWEM.SAS, was written by Karen Spritzer *;
* for SAS 8.0, 3/22/2004. *;
* Modified on 8/23/2004. *;
* Link to code is: *;
* http://www.gim.med.ucla.edu/FacultyPages/Hays/util.htm (hayspowem.sas) *;
* *;
* NOTES: do not alter code in the macro - only modify the macro call. *;
* The macro allows up to 10 scales and a sample call to the *;
* macro is at the bottom of the code. *;
* Note that in the program, scale names > 20 characters are truncated *;
* to 20 to keep table columns in line in the output. *;
* *;
*****************************************************************************;

/*********** DO NOT MODIFY ANYTHING BETWEEN "%MACRO HAYSPOWEM" AND "&MEND HAYSPOWEM" ***********/

%MACRO HAYSPOWEM(
TITLE=,
sd1=,sd2=,sd3=,sd4=,sd5=,sd6=,sd7=,sd8=,sd9=,sd10=,
nscal1=,nscal2=,nscal3=,nscal4=,nscal5=,nscal6=,nscal7=,nscal8=,nscal9=,nscal10=,
nscales=,outfile=);

proc sql;
create table temp
(sd num,
scale char(30));

insert into temp
values(&sd1, &nscal1)
values(&sd2, &nscal2)
values(&sd3, &nscal3)
values(&sd4, &nscal4)
values(&sd5, &nscal5)
values(&sd6, &nscal6)
values(&sd7, &nscal7)
values(&sd8, &nscal8)
values(&sd9, &nscal9)
values(&sd10,&nscal10);

data temp; set temp;
scale=substr(scale,1,20);
if _N_ <= &nscales;
run;

/**** TABLE 1 ****/

data _null_; file "&outfile";

put &TITLE /
" " /
" " /
"Table 1: Sample sizes needed per group to detect differences " /
"between two experimental groups, repeated measures design. " /
" " /
" Number of Points Difference" /
"Scale Name R SD VAR 2 5 10 20 " /
"_________________________________________________________________________ ";
run;

data _null_; file "&outfile" mod; set temp;
r=.60;
rsquare=r*r;
var=sd*sd;

two =15.68*var*(1-rsquare)/ 4;
five =15.68*var*(1-rsquare)/ 25;
ten =15.68*var*(1-rsquare)/100;
twenty=15.68*var*(1-rsquare)/400;

put scale +1 @23 r 4.2 @30 sd 5.2 @37 var 7.2 @46 two 7.0 @53 five 7.0 @60 ten 7.0 @67 twenty 7.0;

run;