topic Re: Dealing with CLASS with more than 2 variables in Statistical Procedures

Dealing with CLASS with more than 2 variables

deleted_user — Wed, 29 Dec 2010 21:31:45 GMT

Hi All,

I have a ' day' variable and it is divided in 'Morning' , 'Noon' and 'Evening'. I have also the 'TimeSpent' in each of these parts. I want to test if there is any statistical difference in the mean time spent in each of the three parts of the 'day'. When I use:-

proc ttest data=data;
class day;
var TimeSpent;
run;

Error:-

The CLASS variable has more than two levels.

Kindly guide how to deal with this.

Kind Regards,
Kritanjli

Re: Dealing with CLASS with more than 2 variables

mfisher — Wed, 29 Dec 2010 23:57:27 GMT

proc glm data=data;
class day;
var TimeSpent;
run;

Re: Dealing with CLASS with more than 2 variables

Ksharp — Thu, 30 Dec 2010 08:50:13 GMT

Just as mfisher said.
Use ' proc glm' + ' means /schette ' statement. '/schette' is what i forgot.

Ksharp

Re: Dealing with CLASS with more than 2 variables

lvm — Thu, 30 Dec 2010 14:35:17 GMT

Actually, it should be:
proc glm data=data;
class day;
model TimeSpent = day;
lsmeans day / pdiff;
run;

Note: you may have clustering with your data, if you are recording/measuring the same individuals at each of these times (a type of repeated measures). That is, with three values per subject (I call it id here). Would have to know more information, but you could handle in a simple way, if
proc mixed data=data;
class id day;
model TimeSpent = day;
random id;
lsmeans day / pdiff;
run;