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Topic: Statistical variability

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	Statistical dispersion - Wikipedia, the free encyclopedia
		In descriptive statistics, statistical dispersion (also called statistical variability) is quantifiable variation of measurements of differing members of a population within the scale on which they are measured.
		An important measure of dispersion is the standard deviation, the square root of the variance (which is itself a measure of dispersion).
		One of the forms in which statistical variability is realized in the empirical sciences is that of differences in repeated measurements of the same quantity.
	en.wikipedia.org /wiki/Statistical_variability (321 words)

	Statistical variability
		Statistical variability is the term used in science to describe the fact that instrument measurements are often not perfectly precise.
		When this happens, scientists usually assume that the quantity being measured is unchanging and stable, and that the variation between measurements is due to observational error.
		This assumption may be false; the risk is that one ignores the possibility that the quantity is indeed dynamic and that the variation observed is intrinsic to the phenomenon.
	www.ebroadcast.com.au /lookup/encyclopedia/st/Statistical_variability.html (192 words)

	Revised ASA Ethics Guidelines-IV
		All professional users of statistical methods should urge clients, employers, researchers, policy makers, journalists, and the public to expect statistical practice to be in accordance with these guidelines and to object when that is not the case.
		Statistical practitioners have ethical obligations to keep methodology publicly available for the benefit of society at large; proprietary reservation of socially useful statistical methodology for private profit, if justified at all, should be as limited as possible in time and scope.
		Statistical practitioners should not be included in authorship or in acknowledgment regarding projects or publications without their explicit permission.
	www.tcnj.edu /~asaethic/asaweb35.html (2618 words)

	Statistical dispersion -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-21)
		In (Click link for more info and facts about descriptive statistics) descriptive statistics, statistical dispersion (also called statistical variability) is quantifiable variation of measurements of differing members of a ((statistics) the entire aggregation of items from which samples can be drawn) population within the scale on which they are measured.
		A measure of statistical dispersion is a (Any rational or irrational number) real number that is zero if all the data are identical, and increases as the data becomes more diverse.
		One of the forms in which statistical variability is realized in the empirical (A particular branch of scientific knowledge) sciences is that of differences in repeated measurements of the same quantity.
	www.absoluteastronomy.com /encyclopedia/s/st/statistical_dispersion.htm (344 words)

	SSES Environmental Statistics
		The traditional views of the scientific method use experimental design to control variability in the presence of responses of interest and explanatory variables, where the three principles of blocking, replication, and randomization are applied.
		Environmental statistics is concerned with the study of variability in the environmental sciences.
		The relevance of environmental statistics to the environmental sciences is in direct proportion to the development of computer-intensive statistical methods on fast workstations and supercomputers.
	www.stat.ohio-state.edu /~sses/sses_env.html (501 words)

	PreK-12 GAISE Draft 1-31-05
		The evidence that statistics is different from mathematics is not presented to argue that mathematics is not important to statistics education or that statistics education should not be a part of mathematics education.
		Accounting of variability with the use of distributions is the key idea in the analysis of data.
		Statistical interpretations are made in the presence of variability and must allow for it.
	it.stlawu.edu /~rlock/gaise/PreK-12GAISEDraft2.htm (6937 words)

	Statistical variability (Site not responding. Last check: 2007-10-21)
		Statistical variability is quantifiable dispersion of measurements of differing members of a population within the scale on which they aremeasured.
		In the physical sciences, such variability may result only from random measurement errors: instrument measurements are oftennot perfectly precise and accurate.
		One may assume thatthe quantity being measured is unchanging and stable, and that the variation between measurements is due to observational error.
	www.therfcc.org /statistical-variability-176473.html (172 words)

	What is a P value?
		Statistical analyses are most useful when you are looking for differences that are small compared to experimental imprecision and biological variability.
		Statistical tests are also based on the assumption that each subject (or each experimental unit) was sampled independently of the rest.
		Statistical calculations combine sample size and variability to generate a confidence interval for the population mean.
	www.graphpad.com /articles/pvalue.htm (2330 words)

	Method for evaluating the timing of digital machines with statistical variability in their delays - Patent 5365463
		For this reason, various known techniques for analyzing designs including significant statistical variation and multiple technologies resort to computational simplifications which, while allowing analysis to be performed in a reasonable amount of time, introduce departures from the true performance of the design, when implemented in manufactured devices.
		The delays and statistical variations in the delays of devices 4, 5 will be correlated to a greater or lesser extent depending on the respective technologies used therein and the senses of the signals propagated through each of the devices.
		In simulation of variation of the performance of real devices, it is a well-known technique, characteristic of so-called Monte Carlo techniques, to use a random number generator to produce a random value which is then used to pick an arbitrary performance value according to a reasonable or observed distribution of performance values.
	www.freepatentsonline.com /5365463.html (9890 words)

	Revised ASA Ethics Guidelines-IV
		Students learning how to apply statistical theory to problems should be encouraged to follow these guidelines whether or not their target professional specialty will be "statistician." Employers, attorneys, and other clients of statistical practitioners have a responsibility to provide a moral environment that fosters use of the ethical guidelines.
		Typically, combine normative understanding of the subject matter issues, statistical protocols that are clearly defined before looking at the data, and power analyses or similar justification of both the practical significance of the study and the sample sizes needed for valid results.
		Statistical practitioners have ethical obligations to keep methodology publicly available for the benefit of society at large; proprietary reservation of statistical methodology for private profit, if justified at all, should be as limited as possible in time and scope.
	www.tcnj.edu /~asaethic/asaweb34.html (2671 words)

	"A very interesting topic": responses (Site not responding. Last check: 2007-10-21)
		Variability is not error per se although it is extremely difficult to separate true performer variability from measurement error.
		The resulting observed variations are directly related to our ability to detect statistical differences since these differences in simple terms are a function of the ratio between effect size (mean differences) and variability (standard error).
		An obvious statistical outcome independent of the practical concerns of grouping individuals who use different performer strategies is that the null hypothesis is often falsely supported producing the outcomes previously discussed.
	isb.ri.ccf.org /biomch-l/archives/biomch-l-1995-06/00117.html (2325 words)

	[No title]
		It has been remarked that uncertainty should be distinguished from variability: Variability is a phenomenon in the physical world to be measured, analysed and where appropriate explained.
		Variability and uncertainty add up to total uncertainty and to avoid confusion it was suggested to rename total uncertainty by indeterminability (Vose, 2000), a terminology adopted in our work.
		The statistical part of indeterminability is variation given structure or in other words, residuals given a model, a common statistical technique to describe variability in a regression model.
	www.knaw.nl /rm2003/p52.doc (746 words)

	VARIABILITY OF NEUROPATHIC AND NON-NEUROPATHIC SUBJECTS WALKING ON A MOTORIZED TREADMILL (Site not responding. Last check: 2007-10-21)
		One limitation of the statistical approach to examining variability is that it implicitly assumes that locomotion can be represented by a sequence of independent strides, and that stride-to-stride variability is a reflection of random noise.
		Variability of movements in frontal plane may also be more important to maintaining stability during locomotion than variability in the sagittal plane.
		The purpose of the present study was to examine in more detail the statistical variability in the sagittal plane treadmill walking data of Cavanagh et al.
	www.asb-biomech.org /onlineabs/abstracts97/122 (1214 words)

	WWU Math Department - Colloquium
		techniques are generally required to estimate the statistical
		variability (often called process variance) in insurance losses.
		use to estimate this variability, as well as some of the pitfalls and
	www.ac.wwu.edu /~mathweb/colloquium/a_052004.htm (99 words)

	Statistical Issues in Toxicokinetic Modeling: A Bayesian Perspective
		Uncertainty and variability in the TK parameter estimates affect potentially all TK model predictions (e.g., estimates of tissue doses); it is necessary to assess both to make predictions useful for risk analysts and decisionmakers.
		Variability is inherent in animal and human populations and cannot be reduced.
		Inference for a larger population is given by the size of the posterior interindividual and intraindividual variances, whose corresponding coefficients of variation were estimated at 33 and 18%, respectively.
	ehp.niehs.nih.gov /members/2000/suppl-5/883-893bernillon/bernillon-full.html (10495 words)

	Statistical variability - Wikipedia
		Statistical variability is the term we use to describe the fact that in science, we often need to use instruments which are not perfectly precise in our application.
		The consequence is that repeated measurements often result in data which are not exactly equal, but are similar.
		When this happens, we usually adopt the attitude that the quantity being measured is stable and that our variation is due to observational error.
	nostalgia.wikipedia.org /wiki/Statistical_variability (222 words)

	EMET 350 ABET2K Goals
		Standard statistical methods are emphasized rather than the mathematical theory of statistical models.
		Students should be able to apply concepts of calculus, differential equations, and probability and statistics to the design and analysis of electromechanical systems.
		Students will be able to use statistical parameters to construct standard statistical quality control charts (Pareto, histograms, frequency, X-bar/R, X-bar/s, Median/R, moving average, etc.) to correctly represent variability of statistical processes.
	www.yk.psu.edu /~dec147/emet350/goals.htm (492 words)

	[No title]
		Statistical Estimation 10.1-10.6 5 Estimators and Estimates 10.1 Interval Estimates of the Mean 10.2 Interval Estimates of Proportion 10.3 Interval Estimates of Variance 10.4 Confidence Intervals for Diff between Means 10.5 Bootstrapping Estimation 10.6 Chapter 11: Test Your Guess!
		Inferential statistics includes selections from fundamental probability, discrete random variables and their probability distributions, continuous random variables and their probability distributions, sampling distributions and the Central Limit Theorem, estimation of parameters, and hypothesis testing.
		A common parameter is one of: population mean the difference of 2 population means a population proportion the difference of 2 population proportions a population variance the ratio of two population variances.
	www.cbu.edu /~rrubin/math308sp01/m308objsp01.doc (3294 words)

	[No title] (Site not responding. Last check: 2007-10-21)
		This paper is concerned with the prediction of statistical variability for the tensile creep strength of unidirectional CFRP by using the statistical variability of tensile CSR strength measured at constant strain rate tests based on the kinetic crack growth law [Christensen and Miyano].
		Furthermore, the statistical variability of the creep rupture times at an arbitrary load level was predicted at two levels of temperatures.
		On the other hand, the creep rupture times at the same load level were experimentally measured at the same two levels of temperatures, and the statistical variability of the creep rupture times was predicted based on the kinetic crack growth law.
	www.sem.org /APP-CONF-AC-List2-Abstract.asp?PaperNo=78 (211 words)

	Scientific data (Site not responding. Last check: 2007-10-21)
		In this sets of tables we show the variability indices $\tau$ -mean, minimum, and maximum values- (Tompkins 1999) and $I$ (Torres, Pessah andRomero, 2001) for the variability of gamma-ray sources.
		Statistical variability of all EGRET sources at low galactic latitudes.
		Variability data for the optical outburst of AO 0235+164 detected on November 1999.
	www.iar.unlp.edu.ar /garra/garra-sdata.html (408 words)

	Knowledge King - Statistical variability (Site not responding. Last check: 2007-10-21)
		Statistical variability is quantifiable dispersion of measurements of differing members of a population within the scale on which they are measured.
		One of the forms in which statistical variability is realized in the emprical sciences is that of differences in repeated measurements of the same quantity.
		This is also seen in the arena of manufactured products; even there, the meticulous scientist finds idiosyncracy of sampled items.
	www.knowledgeking.net /encyclopedia/s/st/statistical_variability_1.html (173 words)

	Self-Similarity Through High-Variability: Statistical Analysis of Ethernet LAN Traffic at the Source Level
		Our explanation is based on new convergence results for processes that exhibit high variability (i.e., infinite variance) and is supported by detailed statistical analyzes of real-time traffic measurements from Ethernet LAN's at the level of individual sources.
		There is, moreover, a simple relation between the parameters describing the intensities of the Noah Effect (high variability) and the Joseph Effect (self-similarity).
		An extensive statistical analysis of high time-resolution Ethernet LAN traffic traces (involving a few hundred active source-destination pairs) confirms that the data at the level of individual sources or source-destination pairs are consistent with the Noah Effect.
	www.comsoc.org /net/private/1997/feb/71_05net01-willinger.html (1311 words)

	Journal of Motor Behavior: Impulse and Movement Space--Time Variability.(Statistical Data Included)@ HighBeam Research (Site not responding. Last check: 2007-10-21)
		Journal of Motor Behavior; 12/1/1999; Newell, Karl M. In 3 experiments, the authors examined movement space-time variability as a function of the force-time properties of the initial impulse in a movement timing task.
		In the range of motion and movement time task conditions, peak force, initial rate of force, and force duration were manipulated either independently or in combination across a range of parameter values.
		The findings showed that (a) impulse variability is predicted well by the elaboration of the isometric force variability scaling functions of L. Carlton, K. Kim, Y. Liu, and K. Newell (1993) to...
	www.highbeam.com /library/doc0.asp?DOCID=1G1:61233623&refid=ip_encyclopedia_hf (188 words)

	SECTION 6 -- GCIP MAP for 1997, 1998 and Outlook for 1999 (Site not responding. Last check: 2007-10-21)
		These statistics consist of 12 seasonal characteristics that are associated with each 1-km NDVI seasonal profile for each year during the period 1989 to 1993, as well as the five-year means throughout the conterminous United States.
		Research on the interannual variability of satellite vegetation indexes, for example, due to the effects of the atmospheric water vapor and aerosols or due to year-to-year weather variations or other factors is a key requirement to ensure the proper use of seasonality data.
		The pore space between the various constituent elements of the soil (sand-silt-clay particles, rock fragments, plant roots, etc.) forms the "reservoir" of water available for meeting the evaporation and transpiration demands at the land surface-atmosphere interface, in addition to being the recharge source for ground water.
	www.joss.ucar.edu /gcip/map_97/section6.html (13622 words)

	hertsdirect.org Advice on the statistical variability of Origin-Destination matrices - 2001 census
		The implementation of the adjustment method in the Origin-Destination statistics has introduced a small element of systematic variation.
		Whilst this effect is small compared to the other components of variation described above, and will not significantly affect the counts for a single area, small systematic differences may become apparent when aggregating results for many areas and comparing the results with counts from other census tables.
		Because of the variability caused by small cell adjustment, it has been found that the output area level matrices are unreliable and must be used with great caution.
	www.hertsdirect.com /yrccouncil/hcc/env/factsfigs/population/census/cenresults/odmatrices/ODMatAdvice (434 words)

	Abstract (Site not responding. Last check: 2007-10-21)
		A number of recent empirical studies of traffic measurements from a variety of working packet networks has convincingly demonstrated that actual network traffic is self-similar or long-range dependent in nature (i.e., bursty over a wide range of time scales) -- in sharp contrast to commonly made traffic modeling assumptions.
		Our explanation is based on convergence results for processes that exhibit high variability (i.e., infinite variance) and is supported by detailed statistical analyses of real-time traffic measurements from Ethernet LAN's at the level of individual sources.
		An extensive statistical analysis of two sets of high time-resolution traffic measurements from two Ethernet LAN's (involving a few hundred active source-destination pairs) confirms that the data at the level of individual sources or source-destination pairs are consistent with the Noah Effect.
	math.bu.edu /people/murad/abstracts/84/84.html (269 words)

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