[R-sig-ME] AR1 within test bouts with random intercept

Thierry Onkelinx thierry@onkelinx @ending from inbo@be
Mon Jan 7 10:22:19 CET 2019

Dear Clark,

Have you tried something like corAR1(form = ~time|subj/period) This uses
explict nesting. Your code uses implicit nesting and lme doesn't handle

Best regards,

ir. Thierry Onkelinx
Statisticus / Statistician

Vlaamse Overheid / Government of Flanders
Team Biometrie & Kwaliteitszorg / Team Biometrics & Quality Assurance
thierry.onkelinx using inbo.be
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Op wo 2 jan. 2019 om 20:40 schreef Kogan, Clark <clark.kogan using wsu.edu>:

> Hi,
> I am trying to fit a linear mixed effects model that has a random effect
> for subject and an AR1 correlation structure for time within period, where
> period is nested within subject. I am happy to treat time as either
> discrete or continuous - the time intervals within a period are all the
> same. I attempt to fit the following model and get an error.
> mod <- lme(agg ~ tx_group + day + tx_group*day, random = ~1|subj,
> correlation = corAR1(form = ~time|subj_period), data = pw)
> Error in lme.formula(agg ~ tx_group + day + tx_group * day, random = ~1 |
> :
>   incompatible formulas for groups in 'random' and 'correlation'
> From a little online reading, it seems that lme likes to have the same
> grouping factor for the random effects and the correlation. I was wondering
> whether there are other tools that are currently available to fit this type
> of correlation structure.
> Thanks,
> Clark Kogan
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