We calculate the life time of a resonance in our recently developed framewo
rk for a test-particle description of transport processes for states with c
ontinuous mass spectra. The result differs from the expression commonly use
d in transport simulations but agrees with the one derived by Danielewicz a
nd Pratt relating the life time to the scattering phase shift. (C) 2001 Els
evier Science B.V. All rights reserved.