# 0.2 The impact of i.j. good on density estimation

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One of three appreciations of I.J. Good's work published in The Good Book: Thirty Years of Conmments, Conjectures and Conclusions by I.J. Good. The book is available in print form from Rice University Press (http://ricepress.rice.edu).

(This module helps introduce The Good Book: Thirty Years of Comments, Conjectures and Conclusions, by I.J. Good . The book is available for purchase from the Rice University Press Store . You can also visit the Rice University Press web site .)

## Density estimation

It is a pleasure to review Jack Good's numerous contributions to the theory and practice of modern statistics.Here, we wish to remember his innovations in the field of nonparametric density estimation.Together with his student R. A. Gaskins, Jack invented penalized likelihood density estimation (Good and Gaskins, 1971).Given the computing resources available at that time, the implementation was truly revolutionary. A Fourier seriesapproximation was introduced, not with just a few terms, but ofttimes thousands of terms. To address the issue ofnonnegativity, the authors solved for the square root of the density. The penalty functions described were ${L}_{2}$ norms of the first and second derivatives of the density's square root.

The first author had the pleasure of attending a lecture by Jack at one of the early Southern Research Conference on Statisticsmeetings and returned to Rice University with a number of questions. For example, isthe square root “trick” valid? Could a closed-form solution be found? Considering such questions led to collaborationswith numerical analyst Richard Tapia and theses by Gilbert de Montricher and the second author. Gilbert wasable to show that the first derivative penalty could be solved in closed form. (Klonias [1982]later provided a wider set of solutions.) But Gilbert also showed that the squareroot trick does not work in general in infinite-dimensional Hilbert spaces, such as those considered here. Scott (1976)examined a finite-dimensional approximation for which the square-root trick does apply. These research findings werecollected in Tapia and Thompson (1978), one of the first surveys of nonparametric density estimation.In this and other venues, Jack's pioneering work led to a large body of research based on splines andother bases.

## Nonparametric density research at rice

Jack's inspiration came at a very fortuitous time for statisticians at Rice. NASA funding had switched from an emphasis on space exploration to that ofagricultural intelligence gathering via remote sensing. (Thompson well remembers Jack in his IDA days walking around Princetonin a trenchcoat, affecting the pose of George Smiley. So Jack might appreciate what follows below.)The idea was to identify and exploit shortages in Soviet grain production.

The NASA prototype solution in 1970 used a huge and clunky multi-spectral scanner that recorded groundreflectivity in twelve channels. This involved flyovers in Kansas from large aircraft.Misclassification rates were running around 25% using the assumption the data were multivariate Gaussian.The solution (before we got into the problem) was to expand the hardware to an even larger twenty-four-channel device.NASA had not run into the heavy-tailed pathologies dealt with by the Princeton Robustness Project, but rather into themixture of distributions problem which the Princetonians did not address. Of course, for the mixture problem under theGaussian assumption, things get worse as the number of channels increases. Thompson was somewhat amazed to find during adrive around in the summer of 1971 that the LARYS group at Purdue and the Willow Run group at Michigan were also treatingthe data as though they were Gaussian.

where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
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