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Communications in Statistics - Theory and Methods Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/lsta20

Properties of doubly-truncated gamma variables a

Christopher S. Coffey & Keith E. Muller

b

a

Dept of Preventive Medicine , Vanderbilt Unive.School of Med , A-1124 Medical Center North, Nashville, Tennessee, 37232-2637 b

Dept. of Biostatictics CB#7400 , University of North Carolina , 3105C McGavranGreenberg, Chapel Hill, North Carolina, 27599 Published online: 27 Jun 2007.

To cite this article: Christopher S. Coffey & Keith E. Muller (2000) Properties of doubly-truncated gamma variables, Communications in Statistics - Theory and Methods, 29:4, 851-857, DOI: 10.1080/03610920008832519 To link to this article: http://dx.doi.org/10.1080/03610920008832519

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COMMtiN. STATIST.-THEORY

METE., 29(4), 851-857 (2000)

Chiistopher S. Coffey

Keith E. Mullc:

A- i 124 ~ e d i c aCenter i North

3 105C McGavran-Greenberg Dept. of Riostatistics, CR#7400 University uf North Czolina Chapel Hill, North Carolina 27599

-n y t nf' Preventive M ~ d i e i n ~ Vanderbi!: Univ. School of Mcd.

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Nashville, Tennessee 37232-2637

-.

- .- irllnca~ed ..-- gamma distribution has been wideiy studied, primai-iiy in Hetesting and reiiabiiiiy settings, Most work has assumed an upper bomd on the i

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support of the random variabie, i. e , t'ne space of the distribution is (0, uj. We consider. a doubiy-truncated gamma rartdom 9-ariable restricted by both a lowcr (1) and upper (u) truncation point, both of which are considered known. We provide sirnp!e f o m s for the densityi cumulative distribution function (CDF), moment . . . generating fimctioii, cumulant generating ~ n c t i o n ,charac:enst:c h n c l i m , and

-

moments.

extend the resuiis to describe tiie dsnsi~y,CDF, and momen& 3of a

doubly-truncated noncentral chi-square variable.

1. lNTRGDtTCTION

The truncated garnna distrib~tionhas heer! wide!y stndied, primarily in lifetesting and reliability settings. Most work has assumed an upper bound on the s~upport of the random variabie. i. e . the space of the distributioii is ( 0 , u j (Johnson; Kotz, and Salakrishnan, !994, $8.!1. We consider a dot?b!=trllncated J SLY-

Copyright O 2000 by Marcel Dekker, Inc.

www.dekker.com

COFFEY .4ND MULLER

552

In study pianning igr linear modeis with Gaussian er~:.ors. detenrrin~ngthe szrno!e size reauired to detect a specified effect w t h scme target p v e r requires

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err;~be aPn!ied ~ ~ piiot stud\,/ i ~ in ~ nrdpr tn p:r_rt~~.t rgaimt m i ~ - ~ p e ~ ~ f inf ~ act2&. The x fir:^! s a q ! sizei ~ !V+ !her? -2i becomes a FGnc;ioii of 'h-.--: ------+ L--.1' :..+--.-' -:I-.& -a -.-, 1L I I G v a ~ I a l w iL ~ L I ~ I I C I I L ~ U ~ IL I~ I L I I I L L I I I ~ I p i LIL ti pi^, v1. .. LoItey and Miiiier 11 k 4s" ,, , rnmwi:c - i . d ; . d

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T.ee. Y . S. 2nd Liz, '1.. K. (1992). ';High Order co,iiish-Fisher E.xp~i;~jio~,"

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Lee, Y . S, znd Li.;

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.ra --7??_249 -.

-rx,

T . K. (1993;). "(zorrection to Aigoriihm AS 26.9: High Order

Expansion," Applied Siilii~fics,42, 268-263. -1 aylor,Comisb-Fisher D. J. and Muller, K. E. (i996). "Bias in Linear iviodei Power and Sample Size Caicuiarions Due to Es-iirnaiing Noncentralitj;," C ~ m ; x u t : i c d o n sir: Statistics: Theor?, and Methods, 25, i595-1610. Wities, J. and Erittain, F. (1990). "The Role oEInternai Pilot Studies in increasing the Efficency of Cilnical Trials," Sf&Sljc.y it: )nne&cine, 9,65-72, Zheng, Q. (i998). "computing Relations Getwee: S:a:istica! M=mer.ts 2nd

Cumulants," 1998 Proceedings of the ASA Statistical Conzputing Section, 165-170. Received August, 1999; Revised December, 1999

Properties of Doubly-Truncated Gamma Variables.

The truncated gamma distribution has been widely studied, primarily in life-testing and reliability settings. Most work has assumed an upper bound on ...
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