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Volume 2, Issue 2, 271-293, 2011 |
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| A Primer on Using Multilevel Models in Clinical and Experimental Psychopathology Research | | | By Andy P. Field (a), Daniel B. Wright (b) | | | (a) School of Psychology, University of Sussex
(b) Psychology Department, Florida International University | | |
| | | Volume 2, Issue 2, 2011, Pages 271-293 | | | doi:10.5127/jep.013711 | | |
| | | Abstract | | | A Multilevel model is a statistical tool for analysing data that has a hierarchical data structure (in other words, data are nested within contexts). This paper describes what a multilevel model is, how it is described mathematically, the advantages of using this data analysis technique, and some practical issues to consider. We then move on to describe the application of multilevel models using two scenarios pertinent to researchers interested in clinical trial analysis and experimental psychopathology research. We describe how to use the software R to run these analyses. | | |
| | | Table of Contents | | | A Primer on Using Multilevel Models in Clinical and Experimental Psychopathology Research
I Already Know How to Analyse My Data, Why Should I Learn Something New?
Overcoming the Independence of Errors Assumption
Homogeneity of Regression Slopes
Missing Data
What is a Multilevel Model?
Fixed and Random Coefficients
The random intercept model
The random slope model
Building a multilevel model
Some Practical Issues
Assessing the Fit and Comparing Models
Types of covariance structures
Assumptions
Sample Size and Power
Centring Variables
Doing Multilevel Models
A Very Brief Guide to R
Example 1: Clinical Trial Data
Initializing the package and importing the data
Fitting a baseline model
Fitting a random intercepts model
Fitting a model with random intercepts and slopes
Example 2: Reaction Time Data
Importing the data
Fitting a baseline model
Modelling covariance structures
Including the time series variable
Fitting a random slopes model
Summary
Further Reading
References
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| | | Correspondence to | | | Prof. Andy P. Field, Child Anxiety Theory and Treatment Laboratory (CATTLab), School of Psychology, University of Sussex, Falmer, Brighton, East Sussex, BN1 9QH. | | |
| | Keywords | | | Multilevel models, clinical data, psychopathology | | |
| | | Dates | | | Received 17 Dec 2010; Revised 21 Jan 2011; Accepted 21 Jan 2011 | | |
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