Open Access
Translator Disclaimer
June 1999 The detection of local shape changes via the geometry of Hotelling's $T^2$ fields
Jin Cao, Keith J. Worsley
Ann. Statist. 27(3): 925-942 (June 1999). DOI: 10.1214/aos/1018031263


This paper is motivated by the problem of detecting local changes or differences in shape between two samples of objects via the nonlinear deformations required to map each object to an atlas standard. Local shape changes are then detected by high values of the random field of Hotelling’s $T^2$ statistics for detecting a change in mean of the vector deformations at each point in the object. To control the null probability of detecting a local shape change, we use the recent result of Adler that the probability that a random field crosses a high threshold is very accurately approximated by the expected Euler characteristic (EC) of the excursion set of the random field above the threshold. We give an exact expression for the expected EC of a Hotelling’s $T^2$ field, and we study the behavior of the field near local extrema. This extends previous results for Gaussian random fields by Adler and $\chi^2$, $t$ and $F$ fields by Worsley and Cao. For illustration, these results are applied to the detection of differences in brain shape between a sample of 29 males and 23 females.


Download Citation

Jin Cao. Keith J. Worsley. "The detection of local shape changes via the geometry of Hotelling's $T^2$ fields." Ann. Statist. 27 (3) 925 - 942, June 1999.


Published: June 1999
First available in Project Euclid: 5 April 2002

zbMATH: 0986.62076
MathSciNet: MR1724036
Digital Object Identifier: 10.1214/aos/1018031263

Primary: 60G60 , 62M09
Secondary: 52A22 , 60D05

Keywords: brain mapping , Euler characteristic , excursion set , Hotelling's $T^2$ , Local extrema , Random fields

Rights: Copyright © 1999 Institute of Mathematical Statistics


Vol.27 • No. 3 • June 1999
Back to Top