I would be grateful for advice about the following problem. It's not directly R-related, but I'm hoping that R will help me analyse the following data. I have a table which indicates the progression of a certain age-related disease. At a certain point in time, a population was sampled; and I have measurements for the age of each individual, and their disease stage. (Disease stage is an ordered factor, none<A<B<C<D.) I hypothesize that the rate of disease-onset depends on age, but that (once the disease has started) its rate of progression depends on the current disease stage and not on age. I would like to plot the data in a sensible way, to let me see if this hypothesis is reasonable, and to let me explore possible functional forms for the two rates. I can see how to plot the rate of disease onset. I could, for example, plot for each age the fraction of people who have acquired the disease by that age. But I don't know how to visualize the rate of disease progression. All suggestions (especially pointers to relevant literature or R packages) gratefully received! Damon.
Perhaps the package msm (Multi-state Markov models in continuous time ) is interesting for you? christian ----- Original Message ----- From: "Damon Wischik" <djw1005 at cam.ac.uk> To: "R-Help" <R-help at stat.math.ethz.ch> Sent: Saturday, July 26, 2003 8:14 PM Subject: [R] A model for disease progression> > I would be grateful for advice about the following problem. It's not > directly R-related, but I'm hoping that R will help me analyse the > following data. > > I have a table which indicates the progression of a certain age-related > disease. At a certain point in time, a population was sampled; and I have > measurements for the age of each individual, and their disease stage. > (Disease stage is an ordered factor, none<A<B<C<D.) > > I hypothesize that the rate of disease-onset depends on age, but that > (once the disease has started) its rate of progression depends on the > current disease stage and not on age. > > I would like to plot the data in a sensible way, to let me see if this > hypothesis is reasonable, and to let me explore possible functional forms > for the two rates. > > I can see how to plot the rate of disease onset. I could, for example, > plot for each age the fraction of people who have acquired the disease by > that age. But I don't know how to visualize the rate of disease > progression. > > All suggestions (especially pointers to relevant literature or R packages) > gratefully received! > > Damon. > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > stat.math.ethz.ch/mailman/listinfo/r-help