| CCM | CVM | SCSVM |
Assumptions | 1. Competition erosion is constant 2. NPD volatility is constant | 1. Competition erosion is stochastic 2. NPD volatility is constant | 1. Competition erosion is stochastic 2. NPD volatility is stochastic |
Governing stochastic process | 1. S(t) follows (2) 2. σS is constant 3. δ is constant | 1. S(t) follows (2) 2. σS is constant 3. δ(t) follows (4) | 1. S(t) follows (2) 2. σS(t) follows (3) 3. δ(t) follows (4) |