PersonAlytics | R Documentation |
The PersonAlytics package provides the simplified user interface for implementing linear mixed effects models for idiographic clinical trials (ICT) data, single case studies, and small N studies with intensive longitudinal designs. Contact us via https://personalytics.rti.org/ for licensing options.
The basic mixed effects model is dv=time+phase+phase*time
with random intercepts and random slopes for time. The phase variable is optional.
Additional independent variables (or covariates) can be included.
The PersonAlytics
package provides the simplified user interface
for implementing this model using gamlss
or lme
. The
primary function of PersonAlytics
is PersonAlytic
.
Key features of the PersonAlytics
package include:
Automated detection of the residual covariance structure.
PersonAlytics
automates model comparisons for determining autocorrelation
structure for all patients or for each patient.
Automated detection of the function form for the time variable.
PersonAlytics
automates model comparisons for determining the functional
form of the relationship between time and the outcome
(i.e., linear vs. quadratic vs. cubic growth models) for all patients or for each patient.
Estimation. The automated covariance structure and function form for time is done using maximum likelihood (ML) estimators. Final results are estimated using restricted maximum likelihood (REML).
High Throughput. When users have a list of outcomes (dependent variables), a list of target covariates, and/or or desire the analyses to be repeated for each individual in the data set, high throughput options automate the model fitting process.
False Discovery Rate Adjustment. When high throughput options are requested, Type I error correction and false discovery rate adjustments are implemented post-implementation across target covariates (and individuals if requested) within each outcome.
Linear and Generalized Linear Mixed Effects Models. Linear mixed effects models
can be fit in either the nlme
framework or the gamlss
approach. The two approaches give nearly identical fixed effects estimates but differ
in their computation of standard errors and random effects. Generalized linear
mixed effects models can be fit using the gamlss
option
(see gamlss.family
). The gamlss
approach also allows models
for dealing with heteroscedasticity implemented by including mixed effects models for
the variance.
See Palytic
Stephen Tueller stueller@rti.org
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