Multivariate Distribution and Quantile Functions, Ranks and Signs: A measure transportation approach
1 hour 8 mins,
331.77 MB,
WebM
640x360,
29.97 fps,
44100 Hz,
666.14 kbits/sec
Share this media item:
Embed this media item:
Embed this media item:
About this item
Description: |
Hallin, M
Tuesday 22nd May 2018 - 11:00 to 12:00 |
---|
Created: | 2018-05-23 10:00 |
---|---|
Collection: | Statistical scalability |
Publisher: | Isaac Newton Institute |
Copyright: | Hallin, M |
Language: | eng (English) |
Distribution: | World (downloadable) |
Explicit content: | No |
Aspect Ratio: | 16:9 |
Screencast: | No |
Bumper: | UCS Default |
Trailer: | UCS Default |
Abstract: | Unlike the real line, the d-dimensional space R^d, for d > 1, is not canonically ordered. As a consequence, such fundamental and strongly order-related univariate concepts as quantile and distribution functions, and their empirical counterparts, involving ranks and signs, do not canonically extend to the multivariate context. Palliating that lack of a canonical ordering has remained an open problem for more than half a century, and has generated an abundant literature, motivating, among others, the development of statistical depth and copula-based methods. We show here that, unlike the many definitions that have been proposed in the literature, the measure transportation-based ones introduced in Chernozhukov et al. (2017) enjoy all the properties (distribution-freeness and preservation of semiparametric efficiency) that make univariate quantiles and ranks successful tools for semiparametric statistical inference. We therefore propose a new center-outward definition of multivariate distribution and quantile functions, along with their empirical counterparts, for which we establish a Glivenko-Cantelli result. Our approach, based on results by McCann (1995), is geometric rather than analytical and, contrary to the Monge-Kantorovich one in Chernozhukov et al. (2017) (which assumes compact supports or finite second-order moments), does not require any moment assumptions. The resulting ranks and signs are shown to be strictly distribution-free, and maximal invariant under the action of transformations (namely, the gradients of convex functions, which thus are playing the role of order-preserving transformations) generating the family of absolutely continuous distributions; this, in view of a general result by Hallin and Werker (2003), implies preservation of semiparametric efficiency. As for the resulting quantiles, they are equivariant under the same transformations, which confirms the order-preserving nature of gradients of convex function.
|
---|
Available Formats
Format | Quality | Bitrate | Size | |||
---|---|---|---|---|---|---|
MPEG-4 Video | 640x360 | 1.93 Mbits/sec | 985.39 MB | View | Download | |
WebM * | 640x360 | 666.14 kbits/sec | 331.77 MB | View | Download | |
iPod Video | 480x270 | 494.48 kbits/sec | 246.28 MB | View | Download | |
MP3 | 44100 Hz | 252.95 kbits/sec | 125.99 MB | Listen | Download | |
Auto | (Allows browser to choose a format it supports) |