search for: n95trt

...aframe called byyr, with ten columns, the first of which is named cnd95. summary(byyr) shows that byyr$cnd95 contains the factor level "tr" 66 times. Also, when I enter byyr$cnd95 at the command line, I can count 66 "tr" elements in the resulting vector. However, when I enter n95trt <- length(byyr$cnd95[byyr$cnd95=="tr"]) n95trt the result is 68! Any ideas why this is happening, and how I can fix the miscount? (That column also contains 69 entries of "c", and (relevantly?) two NA's.) Thanks for any help. Dave Parkhurst

With the problem below, I've discoved that n95trt<-length(byyr$cnd95[byyr$cnd95=="tr"&!is.na(byyr$cnd95)]) does give me the correct count for the number of "tr" entries. (The same behavior occurs for the "c" level of the cnd95 factor.) It appears that byyr$cnd95=="tr" is finding both "tr"...