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Topic: Statistical dispersion

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  Median - Wikipedia, the free encyclopedia   (Site not responding. Last check: 2007-10-20)
In probability theory and statistics, the median is a number that separates the highest half of a sample, a population, or a probability distribution from the lowest half.
When the median is used as a location parameter in descriptive statistics, there are several choices for a measure of variability: the range, the interquartile range, and the absolute deviation.
Calculation of medians is a popular technique in summary statistics and summarizing statistical data, since it is simple to understand and easy to calculate, while also giving a measure that is more robust in the presence of outlier values than is the mean.
www.sterlingheights.us /project/wikipedia/index.php/Median   (915 words)

 Bambooweb: Quantitative marketing research
Then a test statistic must be chosen that will summarize the information in the sample that is relevant to the hypothesis.
The distribution of the test statistic is used to calculate the probability sets of possible values (usually an interval or union of intervals).
If the test statistic is outside the critical region, the conclusion is that there is not enough evidence to reject the hypothesis.
www.bambooweb.com /articles/q/u/Quantitative_marketing_research.html   (1146 words)

 [No title]   (Site not responding. Last check: 2007-10-20)
A measure of statistical dispersion must yield a number that is zero if all the data are identical, and must increase as the data are more diverse.
A very important measure of dispersion is the standard deviation, the square root of the variance.
Other such measures include the statistical range, the interquartile range, and the average absolute deviation, and, in the case of categorical random variables, the discrete entropy.
www.informationgenius.com /encyclopedia/s/st/statistical_dispersion_1.html   (81 words)

 CIVID3 - Book Main Page   (Site not responding. Last check: 2007-10-20)
Statistical significance is the degree to which a sampled result is true of the entire population.
Dispersion of statistical tools describes how your data is spread out or scattered from either side of your central value.
Statistically, what we need to know is how likely it is that we can obtain a relationship of a particular magnitude from a sample, of a given size, assuming there is no such relationship in the population.
www.civid3.com /supplementalstatistics.htm   (6352 words)

 Standard deviation - LearnThis.Info Enclyclopedia   (Site not responding. Last check: 2007-10-20)
In probability and statistics, the standard deviation is the most commonly used measure of statistical dispersion.
We distinguish between the standard deviation σ (sigma) of a whole population or of a random variable, and the standard deviation s of a sample.
In a certain sense, the standard deviation is the "natural" measure of statistical dispersion if the center of the data is measured by the mean.
encyclopedia.learnthis.info /s/st/standard_deviation_1.html   (771 words)

 Polymer Analysis - Title
In these spectroscopic techniques, dispersion is shown by the existence of peak splittings or the presence of a number of chemical species in small amounts.
Statistics are also used to describe the dispersion of chain size, molecular weight, and topological arrangement of tacticity.
The correct answer is that the measured value is of no use without a description of the statistical distribution in the samples as well as a statistical description of the distribution of melting points, i.e.
www.eng.uc.edu /~gbeaucag/Classes/Analysis/Chapter2.html   (2483 words)

 Lecture 11- Measures of Dispersion
Dispersion or "variation" in observations is what we seek to explain.
This is not enough, and we'll discuss several statistics used to measure variation, which differ in their importance.
For mathematical reasons, statistical procedures are based on measures of dispersion that use SQUARED deviations from the mean rather than absolute deviations.
www.janda.org /c10/Lectures/topic03/L11-dispersion/L11-Dispersion.html   (1473 words)

 283-4   (Site not responding. Last check: 2007-10-20)
Dispersion refers to the spatial distribution of organisms, and is a fundamental component of a species' ecology and life history.
Dispersion patterns themselves are affected by the distribution of resources (including sunlight, nutrients, prey species, etc.) in the environment, as well as through the reciprocal influence of species' behavioral characteristics.
One common method of quantifying dispersion patterns involves counting the number of individuals found in each of a large number of quadrats (sampling units used to measure the density of organisms), and then comparing the observed frequency distribution of numbers of individuals per quadrat to that expected under a Poisson distribution.
bioweb.wku.edu /Courses/Biol283/283-4.htm   (1114 words)

 Josselin Garnier's home page
In the random dispersion case the MI of all frequencies of modulation in the normal dispersion region is predicted.
In the anomalous dispersion regime, polarization dispersion widens the unstable bandwidth.
We have developed a statistical formalism which is based on the study of the time-space autocorrelation function of the field.
www.cmap.polytechnique.fr /~garnier/abstracts.html   (5419 words)

 Background Information on the TII&PAD   (Site not responding. Last check: 2007-10-20)
The overall analysis was statistical in nature and utilized state-of-the-art emission rate and dispersion models; statistical release data from the U.S. DOT HMIS (Hazardous Materials Incident Reporting System) database; 5 years of meteorological observations from over 120 locations in United States, Canada and Mexico; and the most current toxicological exposure guidelines.
Release amounts and emission rates into the atmosphere were statistically modeled based on (1) data from the U.S. DOT HMIS database; (2) container types and sizes authorized for transport as specified in 49 CFR ยง172.101 and Part 173; (3) physical properties of the materials involved, and (4) atmospheric data from a historical database.
Atmospheric parameters affecting the dispersion, and the emission rate, were selected in a statistical fashion from a database containing hourly meteorological data from 120 cities in United States, Canada and Mexico.
www.tc.gc.ca /canutec/ERG_GMU/en/Background_TII&PAD.htm   (494 words)

 Morgan Stanley   (Site not responding. Last check: 2007-10-20)
Dispersion and CPI change were remarkably close, because the shock from oil and commodities was transmitted to wages and to other prices through the sharp increase of the money supply that had occurred in 1971-72 -- due to exchange rate policy.
In statistical terms, the sensitivity of dispersion to CPI change declined in the late 1990s -- after an increase in the early 1990s (Exhibit 2).
To the extent that rising dispersion implies that structural factors are at work, the decline of the CPI is more related to structural factors than to monetary factors.
www.morganstanley.com /GEFdata/digests/20030211-tue.html   (1281 words)

 Powell's Books - Statistics in Criminal Justice / With 3"Windows Disk and Study Guide (2ND 03 Edition) by David ...
Statistics is the students' tool to answering questions.
This textbook covers the basics of statistics as they apply to the study of criminal justice, with emphasis on conceptual rather than computational issues.
Chapters discuss displays of data, measuring the central tendency, dispersion, statistical inference, binomial distributions, statistical testing, the chi- square, normal distribution and statistical significance, variance, measures of association, Pearson's correlation coefficient, bivariate regression, multivariate regression, logistic regression, confidence intervals, and statistical power.
www.powells.com /cgi-bin/biblio?inkey=65-0534595081-1   (257 words)

 Descriptive Statistics
Dispersion refers to the idea that there is a second number which tells us how "spread out" all the measurements are from that central number.
At its simplest, the central tendency and the measure of dispersion describe a rectangle that is a summary of the set of data.
Because of its mathematical properties, especially its close ties to probability theory, the normal curve is often used in statistics, with the assumption that the mean and standard deviation of a set of measurements define the distribution.
www.ship.edu /~cgboeree/descstats.html   (1026 words)

 Josselin Garnier's home page
It is shown that a strong dispersion management stabilizes the soliton, while a small anomalous residual dispersion is necessary for preventing from a stochastic resonance phenomenon.
The effect of a random perturbation is shown to depend strongly on the interplay of the correlation length of the perturbation and the kink width.
It is shown that the statistical properties of the refocused pulse depend on a simple set of parameters that describe the correlation degree of the medium.
www.lsp.ups-tlse.fr /Garnier/abstracts.html   (8675 words)

 Statistical phenomena   (Site not responding. Last check: 2007-10-20)
Statistical analysis was performed using Fisher's exact probability...
This is not an attempt at a comprehensive list of statistical topics; see that article.
Fluctuations and Stochastic Phenomena in Condensed Matter: Proceedings of the Sitges Conference on Statistical Mechanics...
hallencyclopedia.com /Statistical_phenomena   (415 words)

 [No title]
statistics, the standard deviation is the most commonly used measure of
It is defined this way in order to give us a measure of dispersion that is (1) a non-negative number, and (2) has the same units as the data.
The term standard deviation was introduced to statistics by Karl Pearson (On the dissection of asymmetrical frequency curves, 1894).
en-cyclopedia.com /wiki/Standard_deviation   (769 words)

 Undergradate Courses
Estimation theory, sufficient statistics, confidence intervals; hypothesis testing, including power function, error types, Neyman-Pearson Lemma, likelihood ratio tests, and hypothesis tests for means and variances; nonparametric tests, including goodness-of-fit tests, sign test, signed-rank test; linear regression and correlation; multiple linear regression; analysis of variance.
This course is an introduction to the use of statistics in nursing research, and their application to clinical and personal decision making.
Introduction to statistics, including measures of central tendency and dispersion, probability, statistical inference and hypothesis testing, regression and correlation, and analysis of variance.
www.iusb.edu /~acadaff/bulletin/bulletin2000/courses2.html   (18586 words)

 Introductory Statistics with Applications in General Insurance - Cambridge University Press   (Site not responding. Last check: 2007-10-20)
This is a new edition of a very successful introduction to statistical methods for general insurance practitioners.
No prior statistical knowledge is assumed, and the mathematical level required is approximately equivalent to school mathematics.
Statistical distributions useful in general insurance work; 6.
www.cambridge.org /catalogue/print.asp?isbn=0521652340&print=y   (226 words)

 Standard Deviation, Variance, Volatility, Statistical, Binomial
The standard deviation (statistics) is not calculated directly using a formula or equation.
A phenomenon is not negatively volatile (or a phenomenon has a good dispersion) if the standard deviation measures closely to the mean average or the median of the data series.
The statistical standard deviation is calculated as the square root of the variance; the variance is the average of the differences from the mean of the series.
www.saliu.com /standard_deviation.html   (3093 words)

 Research in Psychology - DESCRIPTIVE STATISTICS
These estimates can be provided using the mean (the average of the values), the median (the score at the exact middle of a set of values), or the mode (the most frequent occuring value).
Dispersion refers to the spread of the values within a distribution.
The two common measures of dispersion are the range (the highest value minus the lowest value) and the standard deviation (the relation that set of scores has to the mean of the sample).
www.psy.pdx.edu /PsiCafe/Research/Stats-Desc.htm   (354 words)

 Tuan's Homepage   (Site not responding. Last check: 2007-10-20)
In BUS 220, the student is introduced to the subject of business statistics to include the need for quantitative analysis in business, the basic procedures in problem solving, and the sources and types of data used by business firms.
Be familiar with basic statistical terms such as discrete variable, continuous variable, statistical inference, population, sample, and sampling distribution.
Interval estimates for the population mean, and required sample sizes for confidence intervals of the population mean and population proportion.
www.nv.cc.va.us /home/tluong/bus220.htm   (644 words)

 Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations   (Site not responding. Last check: 2007-10-20)
It is shown that the pulse amplitude dispersion may also be determined by a similar expression, which contains a factor with a value close to l, related to the spatial neutron distribution function.
Within a slight deviation, the neutron distribution at a time when the number of neutrons in the reactor is large agrees well with the distribution calculated from its eigenfunctions.
www.osti.gov /energycitations/product.biblio.jsp?osti_id=4798625   (206 words)

 Diabetes: Increased QTc dispersion is related to blunted ... @ HighBeam Research   (Site not responding. Last check: 2007-10-20)
The aim of the present study was to describe associations between QT dispersion and circadian BP variation as well as autonomic function in type 1 diabetic patients.
All statistical tests were two-sided and were carried out at the 5% level of statistical significance.
QT dispersion is presumed to reflect regional repolarization differences in the heart (47,49).
www.highbeam.com /library/doc0.asp?DOCID=1G1:80392713&refid=holomed_1   (3697 words)

Simply, the degree to which the gemstone shows fire or color.
In mass transfer, Dispersive mass transfer is spreading of mass from highly concetrated areas to lower concentrated areas.
This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title.
www.freecaviar.com /search.php?title=Disperse   (142 words)

 Eli Altus   (Site not responding. Last check: 2007-10-20)
In calculating the mechanical response (stresses, displacements, reaction forces) of small (micro) structures, heterogeneity should be taken into account since the typical "element size" (grain in polycrystals, chain bundles in polymers, particles in composite materials etc.) is not negligible compared to the structure dimensions.
"Effective" material properties are not valid and the statistical dispersion of the beam response (causing reliability problems) is inherent.
Average displacements and their variance are found analytically, and their dependence on the statistics of the above random variables is explored.
www.me.gatech.edu /me/events/seminars/Altus.html   (207 words)

 The MCP-PMT   (Site not responding. Last check: 2007-10-20)
Strictly speaking it is the transit time SPREAD of photoelectrons or, better still, the statistical dispersion associated with this spread that affects the time resolution.
As the transit time and corresponding spread become shorter the dispersion decreases and time resolution increases.
The width of the instrument response function in the single photon counting experiment is due also to timing jitter in the electronic components and problems encountered with frequency matching of the signal output of the MCP.
www.chem.rochester.edu /~stc/mcppmt.htm   (426 words)

 JNH Publications   (Site not responding. Last check: 2007-10-20)
Statistical observations of the epoch of reionization (EOR) power spectrum provide a rich data set for understanding the transition from the cosmic "dark ages" to the ionized universe we see today.
Using both the PRHQ and Dispersion statistical techniques, we determined the time delay, core flux ratio, and excess non-varying B image flux density.
We roughly estimate the systematic uncertainty in the joint result from the difference between the 6 cm and 4 cm results, giving 409+-30 days for the PRHQ statistic and 397+-20 days for the Dispersion statistic.
space.mit.edu /RADIO/papers.html   (2901 words)

 Generalized Linear Models: Selected Bibliography
In Statistical Modelling, eds B. Francis, G.U.H. Seeber, P.G.M. van der Heyden and W. Jansen, pp 303-312.
In Statistical Modelling: Proceedings of the 10th International Workshop on Statistical Modelling, eds G.U.H Seeber, B.J Francis, R Hatzinger, G. Steckel-Berger, Springer-Verlag.
Journal of the Royal Statistical Society B, Ma, R. An Orthodox BLUP Approach to Generalized Linear Mixed Models.
www.statsci.org /glm/bibliog.html   (2204 words)

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