The convergence of a position-dependent branching process used as an approximation to a model describing the spread of an epidemic

1976 ◽  
Vol 13 (2) ◽  
pp. 338-344 ◽  
Author(s):  
J. Radcliffe
Keyword(s):  
Branching Process ◽  
Random Variable ◽  
Mean Square ◽  
Malthusian Parameter ◽  
Markov Branching Process ◽  
Geographical Spread ◽  
Mean Square Convergence ◽  
Velocity Of Propagation ◽  
The Mean ◽  
Number Of Individuals

A supercritical position-dependent Markov branching process has been used as an approximation to a model describing the initial geographical spread of a measles epidemic (Bartlett (1956)). Let α be its Malthusian parameter, ß its velocity of propagation, Z(A, t) the number of individuals in the set A at time t, and A√(ßt) = [√(ßt) r: r ∈ A]. The mean square convergence of the random variable W(A, t)= e–αtZ(A√(ßt), t) to a limit variable W(A) is established.

The convergence of a position-dependent branching process used as an approximation to a model describing the spread of an epidemic

1976 ◽  
Vol 13 (02) ◽  
pp. 338-344 ◽  
Author(s):  
J. Radcliffe
Keyword(s):  
Branching Process ◽  
Random Variable ◽  
Mean Square ◽  
Malthusian Parameter ◽  
Markov Branching Process ◽  
Geographical Spread ◽  
Mean Square Convergence ◽  
Velocity Of Propagation ◽  
The Mean ◽  
Number Of Individuals

A supercritical position-dependent Markov branching process has been used as an approximation to a model describing the initial geographical spread of a measles epidemic (Bartlett (1956)). Letαbe its Malthusian parameter,ßits velocity of propagation,Z(A,t) the number of individuals in the setAat timet,andA√(ßt)= [√(ßt)r:r ∈ A]. The mean square convergence of the random variableW(A, t)= e–αtZ(A√(ßt),t) to a limit variableW(A) is established.

Asymptotic behaviour of immigration-branching processes by general set of types. II: Supercritical branching part

1975 ◽  
Vol 7 (03) ◽  
pp. 468-494
Author(s):  
H. Hering
Keyword(s):  
Branching Process ◽  
Branching Processes ◽  
Almost Sure Convergence ◽  
Transition Function ◽  
Mean Square ◽  
Second Moments ◽  
Mean Square Convergence ◽  
The Mean ◽  
Parameter Dependent ◽  
Dependent Probability

We construct an immigration-branching process from an inhomogeneous Poisson process, a parameter-dependent probability distribution of populations and a Markov branching process with homogeneous transition function. The set of types is arbitrary, and the parameter is allowed to be discrete or continuous. Assuming a supercritical branching part with primitive first moments and finite second moments, we prove propositions on the mean square convergence and the almost sure convergence of normalized averaging processes associated with the immigration-branching process.

An age dependent branching process with variable lifetime distribution: The generation size

1974 ◽  
Vol 6 (02) ◽  
pp. 291-308 ◽  
Author(s):  
Robert Fildes
Keyword(s):  
Branching Process ◽  
Random Variable ◽  
Lifetime Distribution ◽  
Mean Square ◽  
Initial Particle ◽  
Age Dependent ◽  
The Mean ◽  
Watson Process ◽  
Number Of Particles

In a branching process with variable lifetime, introduced by Fildes (1972) define Yjk (t) as the number of particles alive in generation k at time t when the initial particle is born in generation j. A limit law similar to that derived in the Bellman-Harris process is proved where it is shown that Yjk (t) suitably normalised converges in mean square to a random variable which is the limit random variable of Znm–n in the Galton-Watson process (m is the mean number of particles born).

An age dependent branching process with variable lifetime distribution: The generation size

1974 ◽  
Vol 6 (2) ◽  
pp. 291-308 ◽  
Author(s):  
Robert Fildes
Keyword(s):  
Branching Process ◽  
Random Variable ◽  
Lifetime Distribution ◽  
Mean Square ◽  
Initial Particle ◽  
Age Dependent ◽  
The Mean ◽  
Watson Process ◽  
Number Of Particles

In a branching process with variable lifetime, introduced by Fildes (1972) define Yjk(t) as the number of particles alive in generation k at time t when the initial particle is born in generation j. A limit law similar to that derived in the Bellman-Harris process is proved where it is shown that Yjk(t) suitably normalised converges in mean square to a random variable which is the limit random variable of Znm–n in the Galton-Watson process (m is the mean number of particles born).

Mean-square and almost-sure convergence of supercritical age-dependent branching processes

1974 ◽  
Vol 11 (04) ◽  
pp. 678-686
Author(s):  
Edgar Z. Ganuza ◽  
S. D. Durham
Keyword(s):  
Branching Process ◽  
Branching Processes ◽  
Age Distribution ◽  
Almost Sure Convergence ◽  
Mean Square ◽  
Malthusian Parameter ◽  
Age Dependent ◽  
Mean Square Convergence ◽  
Watson Process ◽  
Successive Generations

Letting Z(t) be the number of objects alive at time t in a general supercritical age-dependent branching process generated by a single ancestor born at time 0, one achieves (Theorem 1) mean-square convergence of Z(t)/E[Z(t)] provided and , where N(t) is the number of offspring of the initial ancestor born by time t and α is the (positive) Malthusian parameter defined by . If the stronger conditions that (Theorem 2) and hold also, then the convergence is almost-sure. It is of interest that the embedded Galton-Watson process of successive generations need not have a finite mean for the conditions of the above theorems to hold. Similar results are obtained for the age-distribution as well.

Mean-square and almost-sure convergence of supercritical age-dependent branching processes

1974 ◽  
Vol 11 (4) ◽  
pp. 678-686 ◽  
Author(s):  
Edgar Z. Ganuza ◽  
S. D. Durham
Keyword(s):  
Branching Process ◽  
Branching Processes ◽  
Age Distribution ◽  
Almost Sure Convergence ◽  
Mean Square ◽  
Malthusian Parameter ◽  
Age Dependent ◽  
Mean Square Convergence ◽  
Watson Process ◽  
Successive Generations

Letting Z(t) be the number of objects alive at time t in a general supercritical age-dependent branching process generated by a single ancestor born at time 0, one achieves (Theorem 1) mean-square convergence of Z(t)/E[Z(t)] provided and , where N(t) is the number of offspring of the initial ancestor born by time t and α is the (positive) Malthusian parameter defined by . If the stronger conditions that (Theorem 2) and hold also, then the convergence is almost-sure. It is of interest that the embedded Galton-Watson process of successive generations need not have a finite mean for the conditions of the above theorems to hold. Similar results are obtained for the age-distribution as well.

The asymptotic frequencies of the types in a multitype age-dependent branching process allowing immigration

1973 ◽  
Vol 10 (03) ◽  
pp. 652-658
Author(s):  
J. Radcliffe
Keyword(s):  
Renewal Process ◽  
Branching Process ◽  
Almost Sure Convergence ◽  
Mean Square ◽  
Malthusian Parameter ◽  
Age Dependent ◽  
The Mean

The mean square and almost sure convergence of W(t) = e–αt Z(t) is proved for a super-critical multitype age-dependent branching process allowing immigration at the epochs of a renewal process. It is shown that the Malthusian parameter, asymptotic frequencies of types and stationary age distributions are the same for the processes with and without immigration.

The asymptotic frequencies of the types in a multitype age-dependent branching process allowing immigration

1973 ◽  
Vol 10 (3) ◽  
pp. 652-658 ◽  
Author(s):  
J. Radcliffe
Keyword(s):  
Renewal Process ◽  
Branching Process ◽  
Almost Sure Convergence ◽  
Mean Square ◽  
Malthusian Parameter ◽  
Age Dependent ◽  
The Mean

The mean square and almost sure convergence of W(t) = e–αtZ(t) is proved for a super-critical multitype age-dependent branching process allowing immigration at the epochs of a renewal process. It is shown that the Malthusian parameter, asymptotic frequencies of types and stationary age distributions are the same for the processes with and without immigration.

Asymptotic behaviour of immigration-branching processes by general set of types. II: Supercritical branching part

1975 ◽  
Vol 7 (3) ◽  
pp. 468-494
Author(s):  
H. Hering
Keyword(s):  
Branching Process ◽  
Branching Processes ◽  
Almost Sure Convergence ◽  
Transition Function ◽  
Mean Square ◽  
Second Moments ◽  
Mean Square Convergence ◽  
The Mean ◽  
Parameter Dependent ◽  
Dependent Probability

We construct an immigration-branching process from an inhomogeneous Poisson process, a parameter-dependent probability distribution of populations and a Markov branching process with homogeneous transition function. The set of types is arbitrary, and the parameter is allowed to be discrete or continuous. Assuming a supercritical branching part with primitive first moments and finite second moments, we prove propositions on the mean square convergence and the almost sure convergence of normalized averaging processes associated with the immigration-branching process.

A note on the subcritical generalized age-dependent branching process

1976 ◽  
Vol 13 (4) ◽  
pp. 798-803 ◽  
Author(s):  
R. A. Doney
Keyword(s):  
Branching Process ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
Malthusian Parameter ◽  
Age Dependent ◽  
The Mean ◽  
Mean Function ◽  
Necessary And Sufficient

For a subcritical Bellman-Harris process for which the Malthusian parameter α exists and the mean function M(t)∼ aeat as t → ∞, a necessary and sufficient condition for e–at (1 –F(s, t)) to have a non-zero limit is known. The corresponding condition is given for the generalized branching process.

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