swPlot {swCRTdesign}

Plot of Mean Response/Outcome for Stepped Wedge Cluster Randomized Trial (SW CRT)

Description

swPlot returns plot of the mean response versus time based on waves and/or clusters from a SW CRT.

Usage

swPlot(response.var, tx.var, time.var, cluster.var, data, choose.mfrow=NULL,
by.wave=TRUE, combined.plot=TRUE, choose.xlab="Time", choose.main=NULL,
choose.pch=NULL, choose.cex=1, choose.tx.col=NULL, choose.tx.lty = c(2,1),
choose.ncol=2, xlim=NULL, ylim=NULL, choose.tx.pos="topright", choose.legend.pos="right")

Arguments

response.var

numeric(vector): Response (Outcome) variable.

tx.var

numeric(vector): Treatment (Predictor of Interest) variable. Typically, 0=control, 1=intervention, and values greater than 1 correspond to other treatment levels.

time.var

integer(vector): Time (points) variable, corresponding to the time points when data were collected during the SW CRT.

cluster.var

integer(vector): Cluster (identification) variable, corresponding to the cluster where an observation is from.

data

An optional data frame containing (at least) the response, treatment (tx), time, and cluster variables.

choose.mfrow

numeric (vector): Choose mfrow for plot. If NULL, mfrow is automatically assigned based on the plot created. The default is NULL.

by.wave

logical: If TRUE, plot mean response according to each wave. If FALSE, plot mean response according to each cluster. The default is TRUE.

combined.plot

logical: If TRUE, plot mean response on same plot (what is plotted depends on by.wave). If FALSE, plot mean response on separate plots for each wave (what is plotted depends on by.wave). The default is TRUE.

choose.xlab

Choose xlab for plot. The default is "Time".

choose.main

Choose main for plot. If NULL, main is chosen for the user; which is highly recommended. The default is NULL.

choose.pch

Choose pch for plot. If NULL, pch are chosen for the user; which is highly recommended. The default is NULL.

choose.cex

Choose cex for choose.pch. Standard cex option in points() applies. The default is 1.

choose.tx.col

Choose colors for different treatment options. Vector of two colors, corresponding to control and treatment groups, respectively. If NULL, colors are chosen for the unique treatment options in the data supplied. The default is NULL.

choose.tx.lty

Choose line types for different treatment options. Vector of two numbers for lty, corresponding to control and treatment groups, respectively. The default is c(2,1).

choose.ncol

Choose number of columns for non-treatment legend. Standard ncol option in legend() applies. The default is 2.

xlim, ylim

Vectors of length 2 giving x and y axis limits on plot. If NULL, minimum and maximum of summary time and response variables are used, respectively.

choose.tx.pos

Choose where to place treatment colors "legend". Standard legend() positions apply. The default is "topright"; if this covers points, it should be changed.

choose.legend.pos

Choose where to place the non-treatment legend. Standard legend() positions apply. The default is "right"; if this covers points, it should be changed. If "mouseclick", user specifies location with mouse/trackpad by clicking on the plot that appears. Specify NULL to remove legend.

Details

Returns a plot of the mean response versus time with a combination of by wave (TRUE / FALSE) and combined plot (TRUE / FALSE) from a SW CRT. See discussion of number of waves in help file for swSummary.

Author(s)

James P Hughes, Navneet R Hakhu, and Emily C Voldal

References

Hussey MA, Hughes JP. Design and analysis of stepped wedge cluster randomized trials. Contemporary Clinical Trials 2007;28:182-191.

Examples

library(swCRTdesign)
# Example 1 
# Generate binary response with 5 clusters, 4 time points
data.Ex1 <- swSim(swDsn(c(2,2,1)),family=binomial(link="identity"), n=120,
                     mu0=0.25, mu1=0.30,time.effect=0, tau=0.05, gamma=.01)

# Example 1 (Mean Response vs Time, by.wave=TRUE, combined.plot=TRUE)
swPlot(response.var, tx.var, time.var, cluster.var, data.Ex1, by.wave=TRUE,
combined.plot=TRUE, choose.tx.pos="bottomright", choose.legend.pos="bottom")

# Example 2 (Mean Response vs Time, by.wave=TRUE, combined.plot=FALSE)
swPlot(response.var, tx.var, time.var, cluster.var, data.Ex1, by.wave=TRUE,
combined.plot=FALSE, choose.tx.pos="bottomright", choose.legend.pos="bottom")

# Example 3 (Mean Response vs Time, by.wave=FALSE, combined.plot=TRUE)
swPlot(response.var, tx.var, time.var, cluster.var, data.Ex1, by.wave=FALSE,
combined.plot=TRUE, ylim=c(0,0.6), choose.tx.pos="bottomright", choose.legend.pos="topleft")

# Example 4 (Mean Response vs Time, by.wave=FALSE, combined.plot=FALSE)
swPlot(response.var, tx.var, time.var, cluster.var, data.Ex1, by.wave=FALSE,
combined.plot=FALSE, choose.tx.pos="bottomright", choose.legend.pos="bottom")