Dear R help community, I have a version of the data below generated by counting the number of individuals in each state every 2-3 time units for a series of cohorts (sets). States are A, B, C, E and T. It is known that the following transitions are possible A->B, B->C, C->E, B->T, C->T and E->T. The identity of the individuals in each set was not recorded. I am interested in estimating the transition rates or probabilities and sojourn times as a function of covariates. We assume that rates (probabilities) are independent of time. Is there a package to estimate those quantities? Is there a method to estimate those quantities? Do you think a Bayesian approach integrating over all possible paths might work? Everything I read about multi-state modeling packages seems to indicate that it is necessary to know the identity of individuals. time,N,A,B,C,E,T,set,cov1,cov2 199,24,22,2,0,0,0,s1,1,4.65816667 201,24,22,2,0,0,0,s1,3,0.29922222 203,24,22,1,1,0,0,s1,10,9.570125 205,24,21,2,1,0,0,s1,6,9.94370139 207,24,20,3,1,0,0,s1,4,1.34693056 209,24,15,8,1,0,0,s1,2,1.20429167 212,24,14,9,1,0,0,s1,9,8.3008125 214,24,12,10,2,0,0,s1,15,9.14613194 216,24,10,11,3,0,0,s1,8,8.94250694 219,24,4,12,8,0,0,s1,5,0.97334722 221,24,3,12,9,0,0,s1,7,7.29372917 223,24,3,6,12,2,1,s1,17,1.28570139 225,24,1,7,8,5,3,s1,16,1.41599306 227,24,1,4,5,11,3,s1,18,7.07947222 229,24,1,3,2,15,3,s1,14,6.09359028 231,24,0,4,0,17,3,s1,12,4.70666667 233,24,0,4,0,17,3,s1,13,5.31577083 235,24,0,2,0,19,3,s1,11,4.62228472 199,24,19,5,0,0,0,s2,1,4.65816667 201,24,23,1,0,0,0,s2,3,0.29922222 203,24,22,2,0,0,0,s2,10,9.570125 205,24,22,2,0,0,0,s2,6,9.94370139 207,23,21,2,0,0,0,s2,4,1.34693056 209,23,19,3,1,0,0,s2,2,1.20429167 212,23,12,10,1,0,0,s2,9,8.3008125 214,23,10,12,1,0,0,s2,15,9.14613194 216,23,3,18,2,0,0,s2,8,8.94250694 219,23,0,16,7,0,0,s2,5,0.97334722 221,23,0,14,8,0,1,s2,7,7.29372917 223,23,0,5,14,2,2,s2,17,1.28570139 225,23,0,0,18,2,3,s2,16,1.41599306 227,23,0,2,13,2,6,s2,18,7.07947222 229,23,0,0,6,7,10,s2,14,6.09359028 231,23,0,0,3,8,12,s2,12,4.70666667 233,26,0,0,1,13,12,s2,13,5.31577083 235,28,0,0,0,16,12,s2,11,4.62228472 199,24,20,4,0,0,0,s3,1,4.65816667 201,24,22,2,0,0,0,s3,3,0.29922222 203,24,18,5,1,0,0,s3,10,9.570125 205,24,16,7,1,0,0,s3,6,9.94370139 207,24,13,10,1,0,0,s3,4,1.34693056 209,24,8,12,4,0,0,s3,2,1.20429167 212,24,5,14,5,0,0,s3,9,8.3008125 214,24,4,10,10,0,0,s3,15,9.14613194 216,24,2,9,12,1,0,s3,8,8.94250694 219,24,0,8,13,3,0,s3,5,0.97334722 221,24,2,6,5,11,0,s3,7,7.29372917 223,22,0,5,4,12,1,s3,17,1.28570139 225,24,1,3,1,17,2,s3,16,1.41599306 227,24,0,2,1,18,3,s3,18,7.07947222 229,25,0,2,0,20,3,s3,14,6.09359028 231,24,0,2,0,19,3,s3,12,4.70666667 233,24,0,1,1,19,3,s3,13,5.31577083 235,24,0,1,0,20,3,s3,11,4.62228472 Any comment will be appreciated. Regards, Emilio A. Laca, Professor One Shields Avenue, 2306 PES Bldg. Plant Sciences Mail Stop 1 ealaca at ucdavis.edu University of California fax: (530) 752-4361 Davis, California 95616 voice: (530) 754-4083 mobile: (530) 220-5315 Include the Mail stop in the address or mail will be delayed.