Statistical reaction models have been used to fit C-NMR spectra for ethylene/1-octene copolymers and to describe the polymerization reaction probabilities. Ten models ranging in complexity from a one-site Bernoulli probability to multiple site second-order Markov systems were studied. Model parameters were determined by fitting the experimental integrations of replicated spectra using a maximum likelihood method. The best fit to the experimental NMR spectra was obtained with a two-site model, one site producing mainly high-density polymer following a Bernoulli probability model, while the second site allows more incorporation of octene following a chain-end controlled probability described by first-order Markov statistics.