How to Select Study Participants to Include in Your Analyses
The day-level metrics that you created in previous steps will now be averaged over multiple days to produce one record per person. Only data from valid persons will be summarized. A valid person is a participant who has a sufficient number of valid days. Criteria for a valid day and a valid person can be defined by the analyst. In the sample code, a valid day is a day in which the participant wore the monitor for at least 10 hours and a valid person is a participant who has at least 4 valid days. Use the PROC SUMMARY statement to count the total number of valid days and the DATA step to identify valid persons.
Sample Code
*-------------------------------------------------------------------*;
* Define a valid day and a valid person. *;
* NOTE: *;
* to change the definitions on the number of wear hours (wear_hr) *;
* required for a valid day, or the number of valid days (valdays) *;
* required for a valid person, please modify the statements below. *;
*-------------------------------------------------------------------*;
pam_day;
set pam_perday;
valid_day=(wear_hr>=10 ); * assign valid day hours criterion here *;
format valid_day yesno. ;
label valid_day= '10+ hours of wear (yes/no)' ;
run ;
proc summary data=pam_day;
by seqn;
var seqn;
where valid_day= 1 ;
output out =valid
n=valdays; * number of days with 10+ hours of wear *;
run ;
data pam_day;
merge pam_day(in=inall) valid;
by seqn;
if inall;
if valdays= . then valdays= 0 ;
label valdays= 'Number of days with 10+ hours of wear' ;
valid_person=(valdays>=4 ); * assign valid person days criterion here *;
format valid_person yesno. ;
label valid_person = 'At least 4 days with 10+ hours of wear (yes/no)' ;
drop _freq_ _type_;
run ;