Undergraduate · Two-state Markov chains
Two-state Markov chains: State one is favored
Two-state Markov chains: investigate state one is favored with transition 1 → 2: p = 0.2; transition 2 → 1: q = 0.8.
Predict what will happen, press Play, then pause and explain what changed. Every control also works without playback.
Watch the relationship
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Understand what you are seeing
The idea behind the motion.
A distribution can settle into a stationary balance while individuals continue changing state. Starting entirely in state one, the distance from stationarity is multiplied by 1−p−q each step. A negative multiplier causes alternating approaches without making any probability negative. This investigation starts with Transition 1 → 2: p = 0.2; Transition 2 → 1: q = 0.8. Predict the result before playing, then change one parameter while keeping the other fixed to test the reason for the change.
A relationship to keep
π₁=q/(p+q); Pₙ(1)=π₁+(1−π₁)(1−p−q)ⁿ
Read the symbols alongside the explanation. A diagram shows the relationship; the assumptions tell you when it applies.
- STEP 1
Set up the mathematical model
Read p as the probability of leaving state one and q as the probability of returning from state two. The starting case is “State one is favored.”
- STEP 2
Follow the changing quantity
Update the state distribution twelve times and compare its first component with the stationary horizontal line.
- STEP 3
Explain and test the result
Check the balance π₁p=(1−π₁)q. Compare monotone, one-step, and alternating convergence using the sign of 1−p−q.
Your turn to explain
Make a prediction. Test your reasoning.
Keep Transition 1 → 2: p = 0.2; Transition 2 → 1: q = 0.8. Pause the timeline at 100%. Given step = 12, calculate state-one probability, stationary probability, error multiplier. Show the substitution into the displayed formula.
Use the values specified in the question. Reset restores the initial values for this investigation.
Compare your explanation
Balance gives π₁=0.8/(0.2+0.8)=0.8. Starting in state one, Pₙ(1)=π₁+(1−π₁)(1−0.2−0.8)^12=0.8. Results: State-one probability: 0.8; Stationary probability: 0.8; Error multiplier: 0. Decimal values are rounded; retain the original parameters when checking.
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