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Topic: Central moment


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In the News (Fri 10 Jul 09)

  
  Moment (mathematics) - Wikipedia, the free encyclopedia
The second central moment is the variance, the square root of which is the standard deviation.
The third central moment is skewness or the symmetry of the probability distribution.
The central moments beyond the third lack this linearity; in that respect they differ from the cumulants (the first three cumulants are the same as the first moment and the second and third central moments; the higher cumulants have a more complicated relationship with the central moments).
en.wikipedia.org /wiki/Moment_(mathematics)   (416 words)

  
 Moment about the mean - Wikipedia, the free encyclopedia
The third and fourth moments about the mean are used to define the standardized moments which are in turn used to define skewness and kurtosis, respectively.
For n ≥ 2, the nth central moment is translation-invariant, i.e.
For n = 1, the nth cumulant is just the expected value; for n = either 2 or 3, the nth cumulant is just the nth central moment; for n ≥ 4, the nth cumulant is an nth-degree monic polynomial in the first n moments (about zero), and is also a (simpler) nth-degree polynomial in the first n central moments.
en.wikipedia.org /wiki/Moment_about_the_mean   (318 words)

  
 Moment about the mean -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-10-18)
The second moment about the mean is called the (The second moment around the mean; the expected value of the square of the deviations of a random variable from its mean value) variance, and is usually denoted σ
The third and fourth moments about the mean are used to define the (additional info and facts about standardized moment) standardized moments which are in turn used to define (An oblique or slanting asymmetry) skewness and (additional info and facts about kurtosis) kurtosis, respectively.
For n ≥ 2, the nth central moment is translation-invariant, i.e.
www.absoluteastronomy.com /encyclopedia/m/mo/moment_about_the_mean.htm   (429 words)

  
 PlanetMath: moment
Note that the expected value is the first moment of a random variable, and the variance is the second moment minus the first moment squared.
The third central moment divided by the standard deviation cubed is called the skewness
This is version 4 of moment, born on 2001-10-26, modified 2005-02-28.
planetmath.org /encyclopedia/Moment.html   (183 words)

  
 Central limit theorem - Open Encyclopedia   (Site not responding. Last check: 2007-10-18)
Central limit theorems are a set of weak-convergence results in probability theory.
But, this limit is just the characteristic function of a standard normal distribution, N(0,1), and the central limit theorem follows from the Lévy continuity theorem, which confirms that the convergence of characteristic functions implies convergence in distribution.
Thus the central limit theorem can be interpreted as a statement about the properties of density functions under convolution: the convolution of a number of density functions tends to the normal density as the number of density functions increases without bound, under the conditions stated above.
open-encyclopedia.com /Central_limit_theorem   (906 words)

  
 Estimation: Methods and Properties
The approach is based on the idea that the population central moments are known functions of unknown parameters of interest.
In turn, the sample moments are then used in place of the population moments in the known system of equations.
The number of moment conditions is at least as large as the number of unknown parameters.
isc.temple.edu /economics/notes/GenMethMom/MethMom01.HTM   (1004 words)

  
 Tracking cardiac electrical instability by computing interlead heterogeneity of T-wave morphology -- Nearing and ...   (Site not responding. Last check: 2007-10-18)
The square root of the second central moment of simultaneous T waves [from the J point to the end of the T wave (JT interval)] was computed from the superimposed waveforms to measure deviation among the T waves.
Second central moment analysis of TWH was tested for accuracy in simulated ECGs in which TWH was elevated in 50 equal intervals from 0 to 800 µV, constructed as described for Fig.
Second central moment calculation of TWH is not affected by the occurrence of U waves, which obscure the terminal portion of the T wave.
jap.physiology.org /cgi/content/full/95/6/2265   (4120 words)

  
 Results   (Site not responding. Last check: 2007-10-18)
Across subjects the observed third central moment as well as the predicted third central moments for the PE model and the Gamma model differed considerably from the normal distribution.
Therefore, it was decided to take the natural logarithm of the third central moment instead of the third central moment itself.
However, in a number of cases (N=69) the observed third central moment was negative.
baserv.uci.kun.nl /~aven1935/applhtml/node12.html   (240 words)

  
 K. O. Bowman's Recent Publications   (Site not responding. Last check: 2007-10-18)
Moments of the distribution are found, and an algorithm relating the fundamental parameter to the mean.
The moment estimator of the fundamental ratio parameter is defined as a series using Faá di Bruno's formulas for derivatives of a composite function (function of a function).
In general, when moments exist, the dominant term in the fourth central moment of an estimator is three times the square of the asymptotic variance; this leads to the value three for the asymptotic kurtosis.
www.csm.ornl.gov /~bowman/recent.html   (1774 words)

  
 Stat review - Chapter 1
The moments can often be used as an indication of the shape of the pdf and thus the distribution of the random variable.
Normally, the central moments, or moments of the deviation of the random variable from the mean, are used.
Since moments are simply special cases of the expected value, there is a relationship between the various moments and expected values of the random variables.
www.ce.pdx.edu /~roy/tutorial/chap_2/chap_2.htm   (1684 words)

  
 untitled
Meshgrid is used to generate the X and Y arrays for the moment calculation.
The central moment is obtained by shifting the origin to the centroid of the function.
The normalized central moment of order (p+q) is obtained by dividing the central moment of the same order by a normalization factor.
www.cis.rit.edu /class/simg782.old/talkMoments/momentEquations.html   (210 words)

  
 Characterizing the Dimensions of a Mental/Emotional Symptom
We can gather some appreciation of the restrictions and distortions of this "moment of choice" by outward observation of the stimuli and situations to which the organism is particularly sensitive or reactive; and of the outward behaviors that it exhibits.
First, the "moment of choice" is distorted by a disordered sense of idealism, of the way things should be; which means there will be a lot of places where this person collides with the world in unpleasant ways.
These could be as simple and brief as isolated dreams or moments of breakdown of compensatory behaviors while driving in traffic; or they may show up as longer and deeper periods of loss of the ability to compensate during adolescence or progressive life stress.
www.wholehealthnow.com /homeopathy_pro/wt3a.html   (2962 words)

  
 The Central Bulletin: Fall 2001
That humble remark belied the confidence and vision Don Lubbers wielded as Central's president for eight years, qualities that were nurtured during his childhood at Central and from his father, Irwin J. Lubbers, who kept the college afloat through the economic uncertainties of the '30s and early '40s.
The award, which is given to a Central College alumni couple who has enthusiastically supported the mission of the college, reflects not only their financial and vocal support of the college, but their sense of priorities.
Although not a graduate of Central, Moore was recently honored with Central's Honorary Alumna designation, a testament to her support of the college's mission.
www.central.edu /alumni/bulletin/fall2001   (4944 words)

  
 Solution to quiz 7
Therefore #4 has the smallest third central moment and #2 has the largest.
The third central moment is not the skewness, but it is related to the skewness.
(You have to divide the third central moment by the cube of the standard deviation to get the skewness.) Therefore what you learned about skewness early in the course can help you reason about third moments.
www.quantdec.com /envstats/quiz/solution/solution_7a.htm   (604 words)

  
 moment (Statistics Toolbox)   (Site not responding. Last check: 2007-10-18)
returns the central moment of the specified order for the elements of x.
Note that the central first moment is zero, and the second central moment is the variance computed using a divisor of n rather than n-1, where n is the length of the vector,
The central moment of order k of a distribution is defined as:
web.media.mit.edu /~bill/workspace/matlab/toolbox/stats/moment.html   (138 words)

  
 WR 39A & A/Plus: Unit 1 Grading Rubric
SUPERIOR:  A superior paper directly addresses the prompt by focusing on a single, clearly significant moment in which writing or some other form of communication is prominent.
COMPETENT:  A competent paper meets the basic demands of the assignment by presenting a moment that is significant and somewhat vivid.
A competent paper may be uniformly average in all areas, or it may be good in some areas and only marginally passing in others.
eee.uci.edu /faculty/zimmerman/39a-student/unit1_rubric.htm   (473 words)

  
 Nicaragua   (Site not responding. Last check: 2007-10-18)
President Enrique Bolaños of Nicaragua said the countries of Central America are enjoying a period of unprecedented unity, peace and economic integration, and urged international financial institutions to seize the moment.
Central America, he said, "deserves greater attention and economic assistance for the development and prosperity of its people.
The Nicaraguan leader praised the OAS role in Central America, and particularly in his country, in helping to resolve the conflicts of previous decades.
www.oas.org /oasnews/2003/Mar_Apr/English/art5.html   (411 words)

  
 Problems with Moment-Based Techniques for OCR
The two-dimensional moment for a (NxM) discretized image, g(x,y), is mpq = sum_y(y=0; y< M-1) sum_x(x=0; x< N-1) x**p y**q * g(x,y) This Formel is taken von Prokop and Reeves and is also found in all the other papers.
I have equitations to calculate the central moments up to order three from the standard moments, which avoids the problem.
After computing the central moments I normalised them by computing: cmpq_ = cmpq / (cm00 ** gamma) with gamma = (p+q)/2 +1 the first Hu invariant is then hu1 = cm20_ + cm02_.
documents.cfar.umd.edu /newsgroups/ocrarchive/msg00585.html   (666 words)

  
 Descriptions of Region Content
The second central moment is the variance, which describes how similar the intensities are within the region.
The third central moment, skew, described how symmetric the intensity distribution is about the mean.
The moments beyond this are harder to describe intuitively, but they can also describe the texture.
rivit.cs.byu.edu /morse/550-F95/node30.html   (892 words)

  
 Disability Central's Mission   (Site not responding. Last check: 2007-10-18)
Disability Central is not an "organization," but rather a community of people coming together with a common goal, to spread and share relevant, helpful information to people who have disabilities.
Disability Central and it's community know that living with a disability, whether you have the disability, or are a friend or family member can be tough.
Disability Central is committed to providing a world of resources to anyone, disability or not, who needs information in a hassle-free environment.
www.disabilitycentral.org /graphichtml/mission.htm   (284 words)

  
 The American Statistician: The Complications of the Fourth Central Moment.@ HighBeam Research   (Site not responding. Last check: 2007-10-18)
This article illustrates the additional complications in the mathematical formulas involving the fourth central moment in comparison with those involving the first moment, the second central moment, and the third central moment.
In an introductory statistics course, moments and central moments of a random variable are interpreted descriptively.
The first moment (the mean) and the second central moment (the variance) are introduced to describe, respectively,...
highbeam.com /library/doc0.asp?docid=1G1:63607974&refid=ink_tptd_mag   (193 words)

  
 Everyones Favorite Muppet Moment?? - Muppet Central Forum
Secondly, there are just too many moments that I like for me to choose one as my favorite.
I was being polite when I told you about the all-caps thing; the least you could have done was extended me the same courtesy.
And you misunderstood me. I don't have 'one' favorite Muppet moment because there are just so many that I like that it's very hard to choose one out of all of them that I like the best.
forum.muppetcentral.com /showthread.php?t=6297   (1165 words)

  
 Moment Based Dimension Reduction for Multivariate Response Regression  Xiangrong Yin   (Site not responding. Last check: 2007-10-18)
Central subspaces are designed to capture all the information for the regression and to provide a population structure for dimension reduction.
While the central k-th moment subspace captures information from the mean, variance and so on up to the k-th conditional moment of the regression.
In the case of multivariate response regressions, simple nonparametric inverse regression based methods for the estimation of central subspaces, such as sliced inverse regression (SIR) and sliced average variance estimation (SAVE), are not very effective due to the curse of dimensionality.
oregonstate.edu /dept/statistics/seelyconf/abstracts/yin.htm   (221 words)

  
 Computation of Basic Statistics   (Site not responding. Last check: 2007-10-18)
the statistic that measures the center of a sample of data (the first central moment) by adding up the observations and dividing by the number of data points.
It may be thought of as the center of mass or balancing point for the data, i.e., that point at which a ruler would balance if all the data values were placed along it at their appropriate numerical values.
the fourth central moment characterizes how peaked (positive kurtosis or leptokurtic) or flat (negative kurtosis or platykurtic) the distribution is. Kurtosis close to zero is for a balanced distribution with regard to peakedness.
www.nws.noaa.gov /om/csd/pds/pcu2/res/students/Stats/part1/BS_stats.htm   (429 words)

  
 NAMS 2001: Program   (Site not responding. Last check: 2007-10-18)
By using the moment analysis method, the partition coefficient and diffusion coefficient was related to the dimensionless first and second central moments of the elution curve of the solvent respectively.
The validity of the method of moment analysis used for IGC data processing was discussed in terms of the symmetric nature of the elution curves.
Similar to the capillary column IGC, the dimensionless first moment of the elution curve was found to be independent of the carrier gas velocity, while the dimensionless second central moment increased with the increase of the carrier gas velocity.
www.che.utoledo.edu /nams/2001/viewpaper.cfm?ID=21   (310 words)

  
 CENTRAL ASIA - CAUCASUS ANALYST   (Site not responding. Last check: 2007-10-18)
Third, many of the Russian forces hitherto deployed in Tajikistan have been found to be corrupted by the drug trade, and given the unreformed nature of the Russian army and its officer corps, it is not improbable that we could find a replication of this previous experience.
The fact that many of these selfsame elites are still consumed by the belief that Central Asian governments are artificial entities that cannot govern themselves or develop economically or culturally without Russian tutelage also abets this policy of seeking to coerce these governments back into Moscow’s fold.
Likewise, the efforts to project military power into Central Asia for nakedly imperial purposes are unlikely to be affordable or sustainable, or to create reliable allies or security systems in Central Asia.
www.cacianalyst.org /view_article.php?articleid=1308   (956 words)

  
 Spectrum: Get central moment...   (Site not responding. Last check: 2007-10-18)
Thus, the nth central moment is the average of (f - f
It is not impossible to ask for fractional moments, e.g.
For n = 1, the central moment should be zero, since the centre of gravity f
fonsg3.let.uva.nl /praat/manual/Spectrum__Get_central_moment___.html   (214 words)

  
 NMath Stats User's Guide - 3.8 Shape
Again, a biased estimator of the standard deviation is used by default-you can specify the unbiased standard deviation using a value from the BiasType enumeration.
Finally, CentralMoment() returns the moment about the mean of a data set specified by a positive integer order.
The first central moment is equal to zero.
www.centerspace.net /doc/NMath/Stats/user/stats9.html   (141 words)

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