The analysis of plant competition experiments with variable plant dens
ity is discussed based on three published data sets. It is shown how c
onclusions regarding plant community dynamics from typical plant compe
tition experiments can be extended and based on a statistical framewor
k. The data are tested in hyperbolic competition models of decreasing
complexity by a standard hierarchical statistical procedure. Hypothese
s on the shape of the response surface curves, the number of necessary
parameters, and the effects of competition on plant growth were teste
d using maximum likelihood ratio tests. The conditions for coexistence
in a hyperbolic competition model were examined analytically. Using t
he found conditions for coexistence and Bayesian statistics, the proba
bility of the four possible outcomes of two-species competition was es
timated in a competition experiment with Avena fatua and A. barbata.