comparing variables whose observations are semi-exclusive

newtriks — Fri, 02 Sep 2022 18:18:53 GMT

How would I run an anova table for lab usage by year and academic year and get true variances if many cells are empty? My dataset is sorted by graduation year in a 3-year academic program, with lab hours recorded in the following fashion (the actual dataset is much larger: 70 observations and 29 variables)

Student Grad 2016 2017 2018 2019 2020

student1 2018 58 83 108

student2 2018 60 86 103

student3 2018 63 80 110

student4 2019 57 84 113

student5 2019 61 79 117

student6 2019 64 82 109

student7 2020 55 80 117

student8 2020 61 82 121

student9 2020 62 87 116

Any and all help is appreciated. Thanks!

Re: comparing variables whose observations are semi-exclusive

PGStats — Fri, 02 Sep 2022 20:40:15 GMT

ANOVA compares observarions, not variables. So you need to transpose your data first. Something like:

data have;
input Student $   Grad  y2016  y2017   y2018   y2019   y2020;
datalines;
student1  2018   58      83       108 . .
student2  2018   60      86       103 . .
student3  2018   63       80       110  . .
studenta  2018   59       82       106  . .
student4  2019     .        57         84      113 .
student5  2019     .        61         79      117 .
student6  2019     .        64         82      109 .
studentb  2019     .        60         81      115 .
student7  2020     .          .           55        80     117
student8  2020     .          .           61        82     121
student9  2020     .          .           62        87     116
studentc  2020     .          .           57        85     118
;

proc transpose data=have out=temp1 prefix=yr; by student grad notsorted; run;

data temp2;
set temp1;
if yr1;
year = input(substr(_name_,2), 4.);
aYear = year - grad + 3; /* student academic year */
keep student grad year aYear yr1;
rename yr1 = labHours;
run;

proc glm data=temp2;
class aYear year;
model labHours = aYear year / solution;
lsmeans aYear;
lsmeans year;
run;

Note: this is testing for main effects only. Interactions between year and academic year are not estimable.

topic Re: comparing variables whose observations are semi-exclusive in SAS Programming

comparing variables whose observations are semi-exclusive

Re: comparing variables whose observations are semi-exclusive