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A Poisson process approximation

Lemma 10.2.1. It holds that

1 0

[nu]

j=1(Cjn−Zj)

√ℓ([nu])

2

du→p 0, where ℓ(n) = ∑n

j=11/(2j).

Proof of the Lemma 10.2.1. The left-hand side is evaluated by

1 0

n

j=11{j ≤nu}(Cjn−Zj)

√ℓ([nu])

2

du

=

1 0

n

j=1 n

k=1

1{j ≤nu}(Cjn−Zj)1{k ≤nu}(Ckn−Zk)

ℓ([nu]) du

=

n

j=1 n

k=1

1 0

1{j ∨k≤nu}(Cjn−Zj)(Ckn−Zk)

ℓ([nu]) du

n

j=1 n

k=1

1 0

1{j ∨k≤nu}

ℓ([nu]) du|(Cjn−Zj)(Ckn−Zk)|

By the similar way as (9.2.6), the right-hand side is bounded above by 2

log(n) ( 1

log 2 + log log(n) )

|(C1n−Z1)(C1n−Z1)|

− 2 log log 2

log(n) |(C2n−Z2)((C1n−Z1) + (C2n+Z2))| +

n

j=1 n

k=2

2 log log(n)

log(n) |(Cjn−Zj)(Ckn−Zk)|

< 2 log(n)

( 1

log 2 −log log 2 + log log(n) )( n

j=1

|Cjn−Zj| )2

So, it is sufficient to prove that

√log log(n) log(n)

n

j=1

|Cjn−Zj| →p 0.

For any 1 ≤b=b(n)≤n, the triangle inequality yields that

n

j=1

|Cjn−Zj| ≤

b

j=1

|Cjn−Zj|+

n

j=b+1

Cjn+

n

j=b+1

Zj.

By the way similar to the equation (22) in Arratia et al. (1995), fix a good coupling such that the first term in the right-hand side is bounded by the total variation distance which converges to 0 and both of the expectation of the second term and third term are O(log log(n)) where we let b(n) =n/log(n).

This completes the proof.

This lemma yields the following corollary, which is a Poisson process ap-proximation.

Corollary 10.2.1. If Lemma 10.2.1 holds, then it holds that

1 0

[nu]

j=1(Cjn−Zj)

√ℓ([nu])

2

du→p 0.

Proof of the Corollary 10.2.1. Consider random variables Pj ∼ P ois(λj =j) j = 1,2, . . . . By the definition of the median, it holds that

P(Pj < med(Pj))< 1 2. On the other hand, it holds that

P(Pj < j) =e−j

j−1

i=0

ji

i! =jλj.

Teicher (1955) proves that jλj is increasing as j goes larger, which is stated in their second inequality of (8). The convergence (20) in Donnelly et al.

(1991a)

j → 1 2 yields that

1

2j > λj, ∀j = 1,2, . . . . (10.2.1) Since it holds that

j=1

( 1 2j −λj

)

= 1

2log(2),

which is the equation (31) in Donnelly et al. (1991a) and (10.2.1), it holds that

0< sup

u∈[0,1]

(ℓ([nu])−ℓ([nu])) =

n

j=1

( 1 2j −λj

)

=O(1)

and infu∈[0,1]([nu]) = ℓ(1) = 1/e. Thence, we have

1 0

[nu]

j=1(Cjn−Zj)

√ℓ([nu])

2

du

=

1 0

[nu]

j=1(Cjn−Zj)

√ℓ([nu])

2(

1 + ℓ([nu])−ℓ([nu]) ℓ([nu])

) du

1 0

[nu]

j=1(Cjn−Zj)

√ℓ([nu])

2(

1 + supu∈[0,1](ℓ([nu])−ℓ([nu])) infu∈[0,1]([nu])

) du

= (

1 + ℓ(n)−ℓ(n) ℓ(1)

) ∫ 1 0

[nu]

j=1(Cjn−Zj)

√ℓ([nu])

2

du

= (

1 +e

n

j=1

( 1 2j −λj

))

1 0

[nu]

j=1(Cjn−Zj)

√ℓ([nu])

2

du→p 0.

This completes the proof.

This corollary and the functional CLT for a Poisson process yields the Theorem 10.1.1.

Bibliography

Anderson, T.W. and Darling, D.A. (1952). Asymptotic theory of cer-tain “goodness of fit criteria” based on stochastic processes, Ann. Math.

Statist. 23 193–212.

Arratia, R., Barbour, A.D. and Tavar´e, S. (1992). Poisson process approximations for the Ewens sampling formula, Ann. Appl. Probab. 2 519–535.

Arratia, R., Barbour, A.D. andTavar´e, S.(2000). Limits of logarith-mic combinatorial structures, Ann. Probab. 28 1620–1644.

Arratia, R., Barbour, A.D.andTavar´e, S.(2003).Logarithmic Combi-natorial Structures: a Probabilistic Approach. EMS Monographs in Math-ematics. European Mathematical Society (EMS), Z¨urich.

Arratia, R., Stark, D. and Tavar´e, S.(1995). Total variation asymp-totics for Poisson process approximations of logarithmic combinatorial as-semblies, Ann. Probab.23 1347–1388.

Arratia, R. and Tavar´e, S. (1992). Limit theorems for combinatorial structures via discrete process approximations, Random Structures Algo-rithms 3 321–345.

Bhattacharya, P.K., (1987). Maximum likelihood estimation of a change-point in the distribution of independent random variables: general multi-parameter case, J. Multivariate Anal. 23 183–208.

Billingsley, P. (1999). Convergence of Probability Measures. Second edi-tion. John Wiley & Sons, Inc., New York.

Billingsley, P.(2012).Probability and Measure. Anniversary edition. John Wiley & Sons, Inc., Hoboken, NJ.

Brodsky, B.E. and Darkhovsky, B.S. (2000). Non-parametric Statisti-cal Diagnosis: Problems and Methods. Kluwer Academic Publishers, Dor-drecht.

Cs¨org˝o, M., Cs¨org˝o, S., Horv´ath, L. and Mason, D.M. (1986).

Weighted empirical and quantile processes, Ann. Probab.14 31–85.

Chen, J. and Gupta, A. K. (2012). Parametric statistical change point analysis. With applications to genetics, medicine, and finance. Second edi-tion. Birkhuser/Springer, New York.

Cs¨org˝o, M. and Horv´ath, L. (1997). Limit Theorems in Change-point Analysis. John Wiley & Sons, Ltd., Chichester.

Cs¨org˝o, M.,Horv´ath, L.and Shao, Q.-M.(1993). Convergence of inte-grals of uniform empirical and quantile processes,Stochastic Process Appl.

45 283–294.

Dedecker, J. and Merlev`ede, F.(2003). The conditional central limit theorem in Hilbert spaces, Stochastic Process Appl.108 229-262.

DeGregorio, A. andIacus, S. M.(2008). Least squares volatility change point estimation for partially observed diffusion processes,Comm. Statist.

Theory Meth. 37 2342–2357.

Dehling, H.,Franke, B.,Kott, T.andKulperger, R.(2014). Change point testing for the drift parameters of a periodic mean reversion process, Statist. Inference Stoch. Process. 17, 1, 1–18.

DeLaurentis, J. M. and Pittel, B. (1985). Random permutations and Brownian motion,Pac. J. Math. 119 287–301.

Donnelly, P., Ewens, W.J.andPadmadisastra, S.(1991a). Function-als of random mappings: exact and asymptotic results,Adv. Appl. Probab.

23 437–455.

Donnelly, P., Kurtz, T.G. and Tavar´e, S. (1991b). On the functional central limit theorem for the Ewens sampling formula,Ann. Appl. Probab.

1 539–545.

Ewens (1972) The sampling theory of selectively neutral alleles, Theoret.

Population Biol.3 87–112.

Gombay, E. (2008). Change detection in autoregressive time series,J. Mul-tivariate Anal. 99 451–464.

Gombay, E. and Horv´ath, L. (1994). An application of the maximum likelihood test to the change-point problem, Stochastic Process Appl. 50 161–171.

Gombay, E. and Horv´ath, L. (1996). Approximations for the time of change and the power function in change-point models, J. Statist. Plann.

Inference 50 161–171.

Hansen, J.C. (1989). A functional central limit theorem for random map-pings, Ann. Probab. 17 317–332. Correction: (1991). Ann. Probab. 19 1393–1396.

Hansen, J.C. (1990). A functional central limit theorem for the Ewens sampling formula,J. Appl. Probab. 27 28–43.

Horv´ath, L. and Parzen, E. (1994). Limit theorems for fisher-score change processes. In: Carlstein, E., M¨uller, H.-G., Siegmund, D. (eds.) Change-point Problems, IMS Lecture Notes - Monogr. Ser. 23 157–169.

Horv´ath, L. and Rice, G. (2014). Extensions of some classical methods in change point analysis (with discussions), TEST 23 219–290.

Jakubowski, A. (1980). On limit theorems for sums of dependent Hilbert space valued random variables. In Lecture Notes in Statist. 2 178–187, Springer-Verlag, New York.

Khmaladze, E.V. (1979). The use of ω2 tests for testing parametric hy-pothesis, Theory Probab. Appl.24 283–301.

Kutoyants, Y. A. (2004).Statistical Inference for Ergodic Diffusion Pro-cesses.Springer Series in Statistics. Springer-Verlag London, Ltd., London.

LaRiccia, V.andMason, D.M.(1986). Cram´er-von Mises statistics based on the sample quantile function and estimated parameters,J. Multivariate Anal. 18 93–106.

Lee, S., Nishiyama, Y. and Yoshida, N. (2006). Test for parameter change in diffusion processes by cusum statistics based on one-step es-timators, Ann. Inst. Statist. Math. 58 211-222.

Liang, K.Y., Self, S. and Liu, X. (1990). The Cox proportional hazards model with change point: an epidemiologic application, Biometrics 46 783–793.

Liptser, R.S.andShiryaev, A.N.(2001).Statistics of Random Processes I General Theory. Springer-Verlag, Berlin.

Mason, D.M. (1984). Weak convergence of the weighted empirical quantile process inL2(0,1), Ann. Probab. 12 243–255.

Matthews, D.E., Farewell, V.T. and Pyke, R. (1985). Asymptotic score-statistic processes and tests for constant hazard against a change-point alternative,Ann. Statist. 13 583–591.

Merlev`ede, F.(2003). On the central limit theorem and its weak invariance principle for strongly mixing sequences with values in a Hilbert space via martingale approximation, J. Theoret. Probab.16 625–653.

Mihalache, S. (2012). Strong approximations and sequential change-point analysis for diffusion processes,Statist. Probab. Lett. 82, 464–472.

Morel, B. andSuquet, C.(2002). Hilbertian invariance principles for the empirical process under association, Math. Methods Statist. 11 203–220.

Negri, I. and Nishiyama, Y. (2012). Asymptotically distribution free test for parameter change in a diffusion process model,Ann. Inst. Statist. Math.

64 911–918.

Negri, I. and Nishiyama, Y. (2014). Z-process method for change point problems, Quaderni del Dipartimento di Ingegneria dell’informazione e metodi matematici. Serie ”Matematica e Statistica” n. 5/MS 窶 2014.

Dalmine: Universit degli studi di Bergamo. Facolt di Ingegneria. Retrieved from http://hdl.handle.net/10446/30761

Nishiyama, Y. (1999). A maximal inequality for continuous time martin-gales and M-estimation in a Gaussian white noise model,Ann. Statist. 27 675–696.

Nishiyama, Y. (2000). Entropy Methods for Martingales. CWI Tract 128 Centrum voor Wiskunde en Informatica, Amsterdam.

Nishiyama, Y. (2009). Asymptotic theory of semiparametric Z-estimators for stochastic processes with applications to ergodic diffusions and time series, Ann. Statist. 37 3555–3579.

Nishiyama, Y.(2011).Martingale riron ni yoru toukeikaiseki.(In Japanese;

English title: Statistical Analysis by the Theory of Martingales.) Kindaik-agakusha, Tokyo.

Oliveira, P.E. (2012). Asymptotics for associated random variables.

Springer, Heidelberg.

Oliveira, P.E. and Suquet, C.(1995). L2(0,1) weak convergence of the empirical process for dependent variables, In Antoniadis, A. and Oppen-heim, G. (eds.) Wavelets and Statistics, Lecture Notes in Statistics 103 331–344.

Oliveira, P.E. and Suquet, C. (1996). An L2[0,1] invariance principle for LPQD random variables, Port. Math.53 367–379.

Oliveira, P.E. and Suquet, C. (1998). Weak convergence in Lp[0,1] of the uniform empirical process under dependence, Statist. Probab. Lett.39 363–370.

Parthasarathy, K.R. (1967). Probability Measures on Metric Spaces.

Academic Press, New York.

Prohorov, Y.V. (1956). Convergence of random processes and limit theo-rems in probability, Theory Probab. Appl.1 157–214.

Song, J and Lee, S. (2009). Test for parameter change in discretely ob-served diffusion processes, Statist. Inference Stoch. Process. 12 165–183.

Stepanov, V.E. (1969). Limit distributions for certain characteristics of random mappings, Theory Probab. Appl. 14, 612–626.

Suquet, C. and Viano, M.C. (1998). Change point detection in depen-dent sequences: invariance principles for some quadratic statistics, Math.

Methods Statist. 7 157–191.

Teicher, H. (1955). An inequality on Poisson probabilities, Ann. Math.

Statist. 26, 147–149.

Tsukuda, K. (2014). New functional central limit theorems for the Ewens sampling formula and random mappings, preprint.

Tsukuda, K. (2015). A change detection procedure for an ergodic diffusion process, manuscript in preparation.

Tsukuda, K. andNishiyama, Y. (2014). OnL2 space approach to change point problems, J. Statist. Plann. Inference 149 46–59.

Tsukuda, K. and Nishiyama, Y. (2015). Manuscript in preparation.

van der Vaart, A.W.(1998).Asymptotic Statistics. Cambridge University Press, Cambridge.

van der Vaart, A.W. and Wellner, J.A. (1996). Weak Convergence and Empirical Processes: with Applications to Statistics. Springer-Verlag, New York.

Yamato, H. (2013). Edgeworth expansions for the number of distinct com-ponents associated with the Ewens sampling formula, J. Japan Statist.

Soc. 43 17–28.

Acknowledgements

The author would like to state his sincere thanks to those who gave com-ments to the contents and who supported him in various senses.

The author is a Research Fellow of Japan Society for the Promotion of Science. This work is partly supported by JSPS KAKENHI Grant Number 26-1487 (Grant-in-Aid for JSPS Fellows).

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