Question on hierarchical nature and data format using lmer

Thanks Thierry,

I thought so. So this leads on to the next question of how to then specify the random effects structure. Given predictors of study programme (4 levels: physio, med, nurse, speed), clinicA (yes/no), clinicB(yes/no), clinicC(yes/no), clinicD(yes/no), clinicE(yes/no), and s clinic A,B,C are nested in study programme [ie. Some clinics are only offered in some programme), and D,E are crossed across programme (common to all programmes)

Is the following logical? I am using the ordinal package, but the formula follows that of lmer.

clmm (as.factor (Sharing) ~ Programme + clinicA + clinicB + clinicC+ clinicD+ clinicE +
                  (1| Programme) + (1| Programme:clinicA) + (1| Programme:clinicB) + (1| Programme:clinicC) +
            (1| clinicD)  + (1| clinicE) + (1| Programme:clinicD) + (1| Programme:clinicE) ,
                  data = dat,
                  link = "logit",
                  threshold = "equidistant")

Many thanks,
Bernard

-----Original Message-----
From: thierry.onkelinx at inbo.be <thierry.onkelinx at inbo.be>
Sent: 26 June 2018 09:38
To: Bernard Liew (School of Sport Exercise and Rehabilitation Sciences) <B.Liew at bham.ac.uk>
Cc: r-sig-mixed-models at r-project.org
Subject: Re: [R-sig-ME] Question on hierarchical nature and data format using lmer

Dear Bernard,

The typical format is one row of data per observation. If you have one measurement per student, then you need to have a column per clinical placement (with a TRUE or FALSE value).

Best regards,

ir. Thierry Onkelinx
Statisticus / Statistician

Vlaamse Overheid / Government of Flanders INSTITUUT VOOR NATUUR- EN BOSONDERZOEK / RESEARCH INSTITUTE FOR NATURE AND FOREST Team Biometrie & Kwaliteitszorg / Team Biometrics & Quality Assurance thierry.onkelinx at inbo.be Havenlaan 88 bus 73, 1000 Brussel www.inbo.be

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2018-06-25 17:09 GMT+02:00 Bernard Liew <B.Liew at bham.ac.uk>:

Dear Community,

Thank you first for the help. My question pertains to a research design as follow:

200 students in total from 4 schools, undergoing different clinical placements in a semester. There are 5 different plausible clinical placements. This means some students have zero placements, others can have a maximum of three, with any placement combinations. Two out of three clinical placements are restricted to some schools. So some clinical placements are nested within schools, others are crossed across schools.

The response variable is an ordinal measure Likert scale of "sharing". The predictors are school and placement.

Qn to be answered: Does different school and clinical placement alter a student's degree of sharing?

Problem 1: data format

The traditional way to format the data is the long "tidy" method. However, because placements are not unique to an individual, how best should one format the data?

Solution 1 ( I think): make the placement variable into a wide format, so instead of one placement predictor, I now have five different placement predictors. This then appears to change the research question? Is there another solution?

Kind regards,
Bernard


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