Thanks, Achim The cdplot is quite interesting too, though it answers a slightly different question and seems to finess the bandwidth question (maybe not a bad thing).
Here's a similar plot, fleshed out as my others: Where <- factor(c(rep("North America", length(sub1)), rep("Europe", length(sub2)))) Year <- c(sub1, sub2) cdplot(where ~ year, bw = "sj") cdplot(Where ~ Year, bw = "sj", col=gray.colors(2,start=.7), main="Milestones: Place of development" ) abline(v= ref, lty=3, col="blue") laby<- 0.6 + 0.05 * c(0, 1, 2, 3, 5, 3, 5, 2) text(labx, laby, labels=txt1, cex=1.2, xpd=TRUE) rug(sub1, quiet=TRUE, col="red", side=3) rug(sub2, quiet=TRUE) This also solves the little problem I had with offsetting the two rug plots (so as not to rely on color). But I wonder why my main= title does not appear. -Michael Achim Zeileis wrote: > Michael, > > very nice and interesting plots! > > One alternative idea to compare the proportion of milestone items > (that does not really answer the bandwith question) in Europe and North > America might be a conditional density plot. After running your R > source code, you could do: > where <- factor(c(rep("North America", length(sub1)), > rep("Europe", length(sub2)))) > year <- c(sub1, sub2) > cdplot(where ~ year, bw = "sj") > showing the decrease in the European proportion. > > Internally, this first computes the unconditional density as in > plot(density(year, bw = "sj")) > and then the density for Europe with the same bandwidth. > > Best wishes, > Z > > > On Thu, 23 Mar 2006 14:25:53 -0500 Michael Friendly wrote: > > >>I have two series of events over time and I want to construct a graph >>of the relative frequency/density of these events that allows their >>distributions to >>be sensibly compared. The events are the milestones items in my >>project on milestones in the history of data visualization [1], and I >>want to compare trends >>in Europe vs. North America. >> >>I decided to use a graph of two overlaid density estimates with rug >>plots, but then >>the question arises of how to choose the bandwidth (BW) for the two >>series to allow them >>to be sensibly compared, because the range of time and total >>frequency differ >>for the two series. To avoid clutter on this list, I've placed the >>data and R code >>at >>http://euclid.psych.yorku.ca/SCS/Gallery/milestone/Test/kde-bug/mileyears4.R >> >>I have two versions of this graph, one selecting an optimal BW for >>each separately >>and the other using the adjust= argument of density() to >>approximately equate >>the BW to the value determined for the whole series combined. The >>two versions >>(done with SAS) are shown at >> >>http://euclid.psych.yorku.ca/SCS/Gallery/milestone/Test/kde-bug/mileyears32.gif >> >> >>http://euclid.psych.yorku.ca/SCS/Gallery/milestone/Test/kde-bug/mileyears33.gif >> >> >> >>The densities in the first are roughly equivalent to the R code >>d1 <- density(sub1, from=1500, to=1990, bw="sj", adjust=1) >>d2 <- density(sub2, from=1500, to=1990, bw="sj", adjust=1) >> >>the second to >>d1 <- density(sub1, from=1500, to=1990, bw="sj", adjust=2.5) >>d2 <- density(sub2, from=1500, to=1990, bw="sj", adjust=0.75) >> >>The second graph seems to me to undersmooth the more extensive data >>from Europe and undersmooth the data from North America. >> >>- any comments or suggestions? >>- are there other methods I should consider? >> >>I did find overlap.Density() in the DAAG package, but perversely, it >>uses a bw= >>argument to select a B&W/grayscale plot. >> >>thanks, >>-Michael >> >> >>[1] http://www.math.yorku.ca/SCS/Gallery/milestone/ >> >>-- >>Michael Friendly Email: [EMAIL PROTECTED] >>Professor, Psychology Dept. >>York University Voice: 416 736-5115 x66249 Fax: 416 736-5814 >>4700 Keele Street http://www.math.yorku.ca/SCS/friendly.html >>Toronto, ONT M3J 1P3 CANADA >> >>______________________________________________ >>R-help@stat.math.ethz.ch mailing list >>https://stat.ethz.ch/mailman/listinfo/r-help >>PLEASE do read the posting guide! >>http://www.R-project.org/posting-guide.html >> -- Michael Friendly Email: friendly AT yorku DOT ca Professor, Psychology Dept. York University Voice: 416 736-5115 x66249 Fax: 416 736-5814 4700 Keele Street http://www.math.yorku.ca/SCS/friendly.html Toronto, ONT M3J 1P3 CANADA ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html