Two-Coin EM: Log-Likelihood Surface

θ_A
θ_B
Low LL
High LL

True Parameters

Data Generation

EM Algorithm

Click on the plot to set EM starting point

Start: (0.45, 0.55)

End: (0.140, 0.704)

Iterations: 10

Generated Data

Exp 1: 2H/8T (was coin A)
Exp 2: 0H/10T (was coin A)
Exp 3: 2H/8T (was coin A)
Exp 4: 9H/1T (was coin B)
Exp 5: 5H/5T (was coin B)

Legend:

○ White circle = true (θ_A, θ_B)

Red dot = EM start

Green dot = EM convergence

Notice the symmetry along the diagonal — swapping θ_A ↔ θ_B gives the same likelihood.