Hi:

Here's another version of the plot using ggplot2:

g <- ggplot(sleepstudy, aes(x = Days, y = Reaction, group = Subject, colour
= Subject))
g + geom_line(size = 1) + geom_smooth(aes(group = 1), size = 2) + theme_bw()

To get rid of the legend, if you so desire, use
g + geom_line(size = 1) +
     geom_smooth(aes(group = 1), size = 2) + theme_bw() +
     opts(legend.position = 'none')

By default, geom_smooth() uses a loess curve for smoothing; use method =
'lm' outside the aes() call to get a least squares line instead. If you
don't want the useful confidence limits on the smooth :), add se = FALSE to
the geom_smooth() argument list.

I tend to like size = 1 for lines, but the default size produces thinner
lines, if that's what you prefer.

HTH,
Dennis

On Sun, Oct 31, 2010 at 7:01 PM, jlwoodard <john.woodard@wayne.edu> wrote:

>
> I'm trying to understand how to plot individual growth curve trajectories,
> with the overall mean trajectory superimposed (preferably in a slightly
> thicker line, maybe in black) over the individual trajectories.  Using the
> sleepstudy data in lme4, here is the code I have so far:
>
> library(lme4)
> library(lattice)
> xyplot(Reaction ~ Days, data = sleepstudy, group = Subject, type = 'l')
>
> This plot produces the individual growth curves nicely, but I'd like to be
> able to plot the mean for each day (averaged over subjects) on top of this
> graph.
>
> Many thanks in advance for any help/suggestions.
>
> John
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/Mean-and-individual-growth-curve-trajectories-tp3021672p3021672.html
> Sent from the R help mailing list archive at Nabble.com.
>
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