Explore.WS.Corr {CorrMixed}  R Documentation 
This function allows for exploring the withinsubject (testretest) correlation (R) structure in the data, taking relevant covariates into account. Estimated correlations as a function of time lag (= absolute difference between measurement moments t_1 and t_2) are provided as well as their confidence intervals (based on a nonparametric bootstrap).
Explore.WS.Corr(OLS.Model=" ", Dataset, Id, Time, Alpha=0.05, Smoother.Span=.2, Number.Bootstrap=100, Seed=1)
OLS.Model 

Dataset 
A 
Id 
The subject indicator. 
Time 
The time indicator. Should be coded as 1, 2, etc. 
Alpha 
The αlevel to be used in the nonparametric bootstrapbased Confidence Interval for R. Default 
Smoother.Span 
A smoothing (loess) technique is used to estimate R as a function of time lag. The smoother span gives the proportion of points in the plot which influence the smooth at each value. Larger values give more smoothness. For details, see https://stat.ethz.ch/Rmanual/Rpatched/library/stats/html/lowess.html. Defauls 
Number.Bootstrap 
The number of nonparametric bootstrap samples to be used to estimate the Confidence Interval for R. Default 
Seed 
The seed to be used in the bootstrap. Default 
Est.Corr 
The estimated correlations R as a function of time lag. A smoothing (loess) technique is used to estimate R as a function of time lag (based on the output in 
All.Corrs 
A 
Bootstrapped.Corrs 
A 
Alpha 
The α level used in the estimation of the confidence interval. 
CI.Upper 
The upper bounds of the confidence intervals. 
CI.Lower 
The lower bounds of the confidence intervals. 
Wim Van der Elst, Geert Molenberghs, RalfDieter Hilgers, & Nicole Heussen
Van der Elst, W., Molenberghs, G., Hilgers, R., & Heussen, N. (2015). Estimating the reliability of repeatedly measured endpoints based on linear mixedeffects models. A tutorial. Submitted.
# Open data data(Example.Data) # Explore correlation structure Expl_Corr < Explore.WS.Corr(OLS.Model="Outcome~as.factor(Time)+ as.factor(Cycle) + as.factor(Condition)", Dataset=Example.Data, Id="Id", Time="Time", Alpha=.05, Number.Bootstrap=50, Seed=123) # explore results summary(Expl_Corr) # plot with correlations for all time lags, and # add smoothed (loess) correlation function plot(Expl_Corr, Indiv.Corrs=TRUE) # plot bootstrapped smoothed (loess) correlation function plot(Expl_Corr)