Hi! I am trying to get R to run regressions for me of a variable on lagged differences of itself. Specifically: x-x(-1) = a + b1(x(-1)-rx(-2))+b2(x(-4)-rx(-5))+e I need to do this a lot of times, altering the value of r. What I've been trying to do was to use the lag() command to create lagged versions of these variables and then constructing these differences by hand (i.e. creating new variables containing these differences). When I put all of those into the lm() command I get a singularity problem: it seems that R is unlagging the time series as it constructs the object matrix, instead of simply truncating away observations that don't exist for all the series due to the "pushing over" that is happening in the lagging. What do I do? Do I need to truncate these by hand and if yes how? Or is there a different way? Thanks, TM
************************************************************************** When Thomas Edison invented the light bulb he tried over 2000 experiments before he got it to work. A young reporter asked him how it felt to have failed so many times. He said "I never failed once. I invented the light bulb. It just happened to be a 2000-step process."