Problems with Repeated Measures ANOVA

[David Williamson]

Using STATA 13.1 for Mac.

I am trying to figure out what I am doing wrong in trying to analyze this dataset. 60 subjects (each of whom is receiving one of two treatments), each subject completes a questionnaire on three occasions. Dataset is set up in longform:

Treatment Subject Visit Score
1 1 1 23
1 1 2 15
1 1 3 18
2 2 1 17
2 2 2 21
2 2 3 15 etc.

Interested in looking at differences between visits, differences due to treatment, and potential interaction

code: anova score treatment / subject|treatment visit treatment#visit, repeated(visit)

I get the "could not determine between-subject basic unit; use bseunit() option" error. Making me crazy.

What am I doing wrong?

David

[Joseph Coveney]

If the rest of your dataset follows the pattern that you imply in your sample listing, then anova won't give you any trouble. See below for illustration. So, my guess is that your dataset has a problem somewhere down past the six observations that you show. Try creating a scaffold dataset of treatments, participants and visits (as shown below) that does follow the implied pattern, merge it with your dataset, and see whether there is some deviation from the pattern (you can use code similar to that commented out below).

.ÿversionÿ13.1

.ÿ
.ÿclearÿ*

.ÿsetÿmoreÿoff

.ÿversionÿ13.1:ÿsetÿseedÿ`=date("2016-08-15",ÿ"YMD")'

.ÿ
.ÿquietlyÿsetÿobsÿ60

.ÿgenerateÿbyteÿtreatmentÿ=ÿ!mod(_n,ÿ2)ÿ+ÿ1

.ÿgenerateÿbyteÿsubjectÿ=ÿ_n

.ÿquietlyÿexpandÿ3

.ÿbysortÿsubject:ÿgenerateÿbyteÿvisitÿ=ÿ_n

.ÿ
.ÿlistÿinÿ1/6,ÿnoobsÿsepby(subject)ÿabbreviate(20)

ÿÿ+-----------------------------+
ÿÿ|ÿtreatmentÿÿÿsubjectÿÿÿvisitÿ|
ÿÿ|-----------------------------|
ÿÿ|ÿÿÿÿÿÿÿÿÿ1ÿÿÿÿÿÿÿÿÿ1ÿÿÿÿÿÿÿ1ÿ|
ÿÿ|ÿÿÿÿÿÿÿÿÿ1ÿÿÿÿÿÿÿÿÿ1ÿÿÿÿÿÿÿ2ÿ|
ÿÿ|ÿÿÿÿÿÿÿÿÿ1ÿÿÿÿÿÿÿÿÿ1ÿÿÿÿÿÿÿ3ÿ|
ÿÿ|-----------------------------|
ÿÿ|ÿÿÿÿÿÿÿÿÿ2ÿÿÿÿÿÿÿÿÿ2ÿÿÿÿÿÿÿ1ÿ|
ÿÿ|ÿÿÿÿÿÿÿÿÿ2ÿÿÿÿÿÿÿÿÿ2ÿÿÿÿÿÿÿ2ÿ|
ÿÿ|ÿÿÿÿÿÿÿÿÿ2ÿÿÿÿÿÿÿÿÿ2ÿÿÿÿÿÿÿ3ÿ|
ÿÿ+-----------------------------+

.ÿ
.ÿ/*ÿ
>ÿrenameÿtreatmentÿTreatment
>ÿmergeÿ1:1ÿsubjectÿvisitÿusingÿ<yourÿdataset>
>ÿassertÿ_mergeÿ==ÿ3
>ÿassertÿtreatmentÿ==ÿTreatment
>ÿexit
>ÿ*/
.ÿ
.ÿversionÿ13.1:ÿgenerateÿdoubleÿscoreÿ=ÿruniform()

.ÿ
.ÿanovaÿscoreÿtreatmentÿ/ÿsubject|treatmentÿvisitÿtreatment#visit,ÿrepeated(visit)

ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿNumberÿofÿobsÿ=ÿÿÿÿÿÿÿÿ180ÿÿÿÿR-squaredÿÿÿÿÿ=ÿÿ0.2772
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿRootÿMSEÿÿÿÿÿÿ=ÿÿÿÿ.310106ÿÿÿÿAdjÿR-squaredÿ=ÿ-0.1153

ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿSourceÿ|ÿPartialÿSSÿÿÿÿÿÿÿÿÿdfÿÿÿÿÿÿÿÿÿMSÿÿÿÿÿÿÿÿFÿÿÿÿProb>F
ÿÿÿÿÿÿÿ------------------+----------------------------------------------------
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿModelÿ|ÿÿ4.2788465ÿÿÿÿÿÿÿÿÿ63ÿÿÿÿ.0679182ÿÿÿÿÿÿ0.71ÿÿ0.9351
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ|
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿtreatmentÿ|ÿÿ.06986714ÿÿÿÿÿÿÿÿÿÿ1ÿÿÿ.06986714ÿÿÿÿÿÿ1.01ÿÿ0.3197
ÿÿÿÿÿÿÿsubject|treatmentÿ|ÿÿ4.0218232ÿÿÿÿÿÿÿÿÿ58ÿÿÿ.06934178ÿÿ
ÿÿÿÿÿÿÿ------------------+----------------------------------------------------
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿvisitÿ|ÿÿ.08538462ÿÿÿÿÿÿÿÿÿÿ2ÿÿÿ.04269231ÿÿÿÿÿÿ0.44ÿÿ0.6426
ÿÿÿÿÿÿÿÿÿtreatment#visitÿ|ÿÿ.10177154ÿÿÿÿÿÿÿÿÿÿ2ÿÿÿ.05088577ÿÿÿÿÿÿ0.53ÿÿ0.5905
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ|
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿResidualÿ|ÿÿ11.155213ÿÿÿÿÿÿÿÿ116ÿÿÿ.09616563ÿÿ
ÿÿÿÿÿÿÿ------------------+----------------------------------------------------
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿTotalÿ|ÿÿ15.434059ÿÿÿÿÿÿÿÿ179ÿÿÿÿ.0862238ÿÿ


Between-subjectsÿerrorÿterm:ÿÿsubject|treatment
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿLevels:ÿÿ60ÿÿÿÿÿÿÿÿ(58ÿdf)
ÿÿÿÿÿLowestÿb.s.e.ÿvariable:ÿÿsubject
ÿÿÿÿÿCovarianceÿpooledÿover:ÿÿtreatmentÿÿ(forÿrepeatedÿvariable)

Repeatedÿvariable:ÿvisit
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿHuynh-Feldtÿepsilonÿÿÿÿÿÿÿÿ=ÿÿ1.0481
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ*Huynh-Feldtÿepsilonÿresetÿtoÿ1.0000
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿGreenhouse-Geisserÿepsilonÿ=ÿÿ0.9951
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿBox'sÿconservativeÿepsilonÿ=ÿÿ0.5000

ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ------------ÿProbÿ>ÿFÿ------------
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿSourceÿ|ÿÿÿÿÿdfÿÿÿÿÿÿFÿÿÿÿRegularÿÿÿÿH-FÿÿÿÿÿÿG-GÿÿÿÿÿÿBox
ÿÿÿÿÿÿÿ------------------+----------------------------------------------------
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿvisitÿ|ÿÿÿÿÿÿ2ÿÿÿÿÿ0.44ÿÿÿ0.6426ÿÿÿ0.6426ÿÿÿ0.6416ÿÿÿ0.5079
ÿÿÿÿÿÿÿÿÿtreatment#visitÿ|ÿÿÿÿÿÿ2ÿÿÿÿÿ0.53ÿÿÿ0.5905ÿÿÿ0.5905ÿÿÿ0.5897ÿÿÿ0.4699
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿResidualÿ|ÿÿÿÿ116
ÿÿÿÿÿÿÿ-----------------------------------------------------------------------

.ÿ
.ÿexit

endÿofÿdo-file


.

[David Williamson]

that helped. thanks!