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State probability

As explained in Statistics Every Programmer Needs

A state probability is the probability that a process or system occupies a particular state during a specified period.

A state probability measures the likelihood that a process occupies a particular state during a specified period. In Markov analysis, states must be collectively exhaustive and mutually exclusive, so each system instance belongs to exactly one state. section 11.2

Represent the probabilities as a vector π = (π₁, π₂, …, πₙ), where πᵢ is the probability of occupying state i. The entries sum to 1, and periods must use consistent units such as days, weeks, quarters, or years. section 11.2 section 11.2.1

Use state probabilities to:

  • Describe the initial distribution of a system before transitions occur. section 11.2
  • Combine current state probabilities with transition probabilities to forecast how a distribution changes over time. section 11.2.1
  • Translate market shares into probabilities when each consumer belongs to one carrier state. section 11.2.1

Four-carrier market distribution

Assign Horizon 0.40, TeleConnect 0.35, AmeriCon 0.20, and USAMobile 0.05. The vector (0.40, 0.35, 0.20, 0.05) describes the probability that a randomly selected consumer subscribes to each carrier in period 0; its entries sum to 1. section 11.2.1

How Statistics Every Programmer Needs covers it

How deep it goes
Defines vectors, state constraints, period indexing, and a worked market-share example, but does not derive transition calculations.
Examples
Uses a running-versus-not-running engine and a four-carrier cellular market-share vector.
What it assumes
Assumes basic probability and state modeling while teaching exclusive state definitions, vector notation, and period indexing.
What you can do after
Apply via a state-probability vector to represent an initial distribution and interpret market shares as state likelihoods.
How it connects
Connects state probabilities to Markov analysis, transition probabilities, market share analysis, and churn.

Related concepts

This explainer was generated by Manning's knowledge graph from the text of Statistics Every Programmer Needs. The section links point to the parts of the book it draws on.