[YPNG] YPNG Friday 12 April 2019

[Sekhar Tatikonda]

Hi Everyone,

John Hartigan will talk this Friday about:

The mean shift method leads to clusters in which the mean of the data
within a sphere
lies at the center of the sphere.  The DP ( please suggest acronym)  test
for the existence
of a population mode within the sphere is based on the variance within the
sphere being
small enough. The null hypothesis is taken from the spherical tree
distribution -- a mixture
of uniform distributions over spheres which have the tree property that
each pair of spheres
are disjoint, or one includes the other.  The test is applied to the
distribution of orbital radius
and inclination of 500000 asteroids of greater than 1km diameter -- some of
which could crash
into the earth at any moment, so you had better come and check it out
before they do!
A version of the test applies to k-means clusters also.

See you Friday at 11am in the Stat's classroom (unless the asteroids see us
first.)

Regards,
sekhar
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