In mathematical statistics, shifts in probability distributions often reveal deeper structures. In particular, the connection between the simplicity of geometric distribution and the complexity of stage-type distribution provides a wonderful journey to understand random processes. How does the stage distribution evolve based on the geometric distribution to become a more complex and applicable distribution? This is the focus of our discussion today.
A step distribution is a probability distribution that results from a sequence of one or more interrelated geometric distributions, or steps, in a system.
The phase distribution can be viewed as a tool for describing random processes that evolve from the states of an absorbing Markov chain. In particular, this Markov chain has one absorbing state, and the rest of the states are transient. This allows the stage-type distribution to be viewed as the distribution of first-pass times to an absorbing state in a finite-state Markov chain.
The behavior of a Markov chain can only be fully characterized if the transition probability matrix between states in the chain has certain properties.
For a fixed terminated Markov chain, we can define the distribution by the upper left square in its transition probability matrix. These features show how phase-type distributions are strongly structured and can exhibit richer statistical properties. This is why such distributions are often used to model queuing systems, stochastic processes in economics, and even have a non-negligible influence in biostatistics.
Both the cumulative distribution function and the density function of a distribution are important components of these procedures and help us better understand the probability of an event occurring.
Special cases of stage-type distributions each exhibit different probabilistic behaviors, expanding our application horizons. When we explore some special cases, such as degenerate distribution, geometric distribution, and negative binomial distribution, we can find that these distributions are not only theoretical models of random processes, but also important tools in practical applications. The degenerate distribution can be viewed as a special case of zero phase, while the geometric distribution is a typical case of one phase. The negative binomial distribution can be viewed as a sequence of two or more identical phases.
The flexibility of the phase distribution enables it to serve as the basis for modeling more complex random phenomena, which has been verified in many practical applications.
The many applications of stage distribution reflect the profound understanding of random processes in modern statistics. From queuing models to economic models, its application is becoming more and more extensive. The foundations of these theories stem from a good grasp of geometric distribution, which further promotes the application of mathematics and statistics in various fields.
In summary, the transition from geometric distribution to phase-type distribution is not only a mathematical leap, but also an important leap in understanding random processes. As this process deepens, we can't help but wonder: Can such a transformation lead us to discover more randomness and structure in future applications?