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Topic: Coefficient of variation


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  Coefficient of variation - Wikipedia, the free encyclopedia
In probability theory and statistics, the coefficient of variation (CV) is a measure of dispersion of a probability distribution.
The coefficient of variation is a dimensionless number that allows comparison of the variation of populations that have significantly different mean values.
The coefficient of variation is often used when discussing the normal distribution for positive mean values with the standard deviation significantly less than the mean.
en.wikipedia.org /wiki/Coefficient_of_variation   (314 words)

  
 Coefficient of Variation   (Site not responding. Last check: 2007-11-06)
The coefficient of variation is simply the standard deviation of a variable divided by the mean of the variable.
Because variances and standard deviations are used to measure error, and because these values are sensitive to the absolute scale of the variable, coefficients of variation are often reported.
Coefficients of variation have the influence of the overall magnitude of the data removed.
espse.ed.psu.edu /espse/hale/507Mat/definitions/cofvar.html   (72 words)

  
 Coefficient of variation   (Site not responding. Last check: 2007-11-06)
The coefficient of variation as a percent is
You are quite right that the coefficient of variation is unit free, but only if the mean and standard deviation are measured in the same units.
= 0.0007 meters and the coefficient of variation is
mathcentral.uregina.ca /QQ/database/QQ.09.01/carmen1.html   (247 words)

  
 Patient Puzzlers for Healthcare
Although this chapter on coefficient of variation is not one that Dr. Tahl has studied yet, he feels compelled to respond, especially since the entire class is looking expectantly at him and waiting for his answer.
Coefficient of variation is a measure of how much variation exists in relation to the mean, so it represents a highly useful—and easy—concept in data analysis.
The coefficient of variation provides a reference, by looking at the ratio of a standard deviation to a mean.
www.pqsystems.com /healthcare/PatientPuzzlers_CoefficientofVariation.php   (583 words)

  
 Coefficient Of Variation---Feb '98 Problem of the Month
For normal (Gaussian) distributions, the coefficient of variation measures the relative scatter in data with respect to the mean.
For example, the variation in the amount of pocket change compared to the average amount of money you have in your wallet may be small to medium when measured by the coefficient of variation.
The coefficient of variation for the Weibull distribution depends upon the shape factor, beta.
www.barringer1.com /feb98prb.htm   (1882 words)

  
 Coefficient of variation (1995).   (Site not responding. Last check: 2007-11-06)
(I suppose because flab means greater variation is possible than in the case of bone.) I mean to say that the rule is approximate.
Convert the numbers from C to F or vice versa.
The CV will change, but the underlying variation is the same.) Hope this helps, John.
www.pitt.edu /~wpilib/statfaq/95cv.html   (288 words)

  
 Measures of Dispersion: Coefficient of Variation   (Site not responding. Last check: 2007-11-06)
The coefficient of variation measures variability in relation to the mean (or average) and is used to compare the relative dispersion in one type of data with the relative dispersion in another type of data.
This reads as 'the coefficient of variation is equal to the standard deviation divided by the mean, multiplied by 100 (to produce a percentage).
Since we already calculated the standard deviation and mean for the previous lesson, let's use those numbers to determine the coefficient of variation.
jimwright.org /WebEd/u02/we020304.htm   (198 words)

  
 Random variation of cell parameters
In studying synchrony, parameters to vary randomly were chosen in order to have heterogeneity of cell size and growth rate in the culture.
For the coefficient of variation of the volume-at-division, a typical value of 0.1 (Koch and Schaechter, 1962; Koch, 1993; Koch, 1996) was used.
Variation of volume-at-division can be regarded as an imprecision of volume measurement by the cell and broadens the size distribution and more so the age distribution.
www.cbc.yale.edu /release/bacsim/bacillus.old/node33.html   (246 words)

  
 Coefficient   (Site not responding. Last check: 2007-11-06)
In mathematics, a coefficient is a multiplicative factor that belongs to a certain object such as a variable, a basis vector, a basis function and so on.
Another meaning of coefficient is that of an important number that characterizes some property of a technical or scientific object.
Exact Confidence Bounds on a Normal Distribution Coefficient of Variation Obtains a two-sided confidence interval on a coefficient of variation for data from a normal distribution.
www.serebella.com /encyclopedia/article-Coefficient.html   (760 words)

  
 Coefficient of Variation
The coefficient of variation is the ratio of the standard error to the estimate.
The coefficients of variation for row proportions and column proportions are computed similarly.
The coefficients of variation for row totals, column totals, and the overall total are computed similarly.
support.sas.com /91doc/getDoc/statug.hlp/surveyfreq_sect22.htm   (142 words)

  
 Coefficient of Variation   (Site not responding. Last check: 2007-11-06)
Coefficient of variation is a measure of relative variability useful for comparing two or more assets with differing expected returns
Coefficient of Variation (CV) is computed as follows:
The higher the coefficient of variation, the greater the risk
www.humboldt.edu /~aa3/fin315/chapt6/sld020.htm   (38 words)

  
 CHANGES IN VERTICAL GROUND REACTION FORCE DURING ENDURANCE RUNNING TO EXHAUSTION ON A TREADMILL   (Site not responding. Last check: 2007-11-06)
A coefficient of variation was determined for each variable and averaged across the six subjects at each time point.
An increase in the coefficient of variation for the loading rate might be associated with decreased control of the leg musculature resulting in variable leg stiffness on impact, although the general trend was for the impact force to increase (implying a stiffer leg).
Impact peak force coefficient of variation decreased, while force magnitude generally increased, possibly indicative of the presence of an upper boundary to impact force sustainable by the body under the given conditions.
www.asb-biomech.org /onlineabs/abstracts99/069   (673 words)

  
 THE CORRELATION COEFFICIENT
Chapter 10 is a discussion of different types of correlation coefficients and should be useful for understanding a particular coefficient in the context of its alternatives.
As with the correlation coefficient derived in Chapter 3, it would be desirable to have some measure which would range between something like 1.00 for perfect correlation, -1.00 for perfect negative correlation, and zero for no correlation.
We saw that the variation of a variable could be pictured as a vector and covariation as codirectionality between vectors.
www.mega.nu:8080 /ampp/rummel/uc.htm   (11715 words)

  
 Coefficient of variation   (Site not responding. Last check: 2007-11-06)
The coefficient of variation expresses the standard deviation as a percentage of the sample mean.
The coefficient of variation, however, will be the same in both cases as it does not depend on the unit of measurement.
The coefficient of variation filter is used to measure the consistency of the gene across all experiments.
mathcentral.uregina.ca /QQ/database/QQ.09.05/jan1.html   (363 words)

  
 Managers' Monitoring Manual | CV Tools   (Site not responding. Last check: 2007-11-06)
Seeing how variable a particular taxonomic group is (along with other variables such as geographic area, sex/age class, etc.) can help determine the sample size you should set when monitoring that taxonomic group.
Variance in counts of animals over space and time is the major determinant of how many samples are needed for a program to be effective.
A coefficient of variation (CV) is calculated by dividing the standard deviation by the mean.
www.pwrc.usgs.gov /monmanual/cvs   (323 words)

  
 ECB: Coefficients of cross-country variation
The coefficient of variation is computed as the standard deviation divided by the euro area interest rate, thus adjusting for the fact that the standard deviation is influenced by the level of the euro area rate.
The weighted variance is the squared deviations between the national and euro area MFI interest rates, calculated according to the national share in the total euro area business volume for a given instrument category.
By measuring, on a monthly basis, the variation of national interest rates around the euro area MFI interest rate (“euro area MIR”) adjusted for the level of the euro area rate, the coefficient of variation allows further a comparison of different MIR indicators.
www.ecb.int /stats/money/interest/coeff/html/index.en.html   (529 words)

  
 TWO-SAMPLE LOG-NORMAL   (Site not responding. Last check: 2007-11-06)
The calculations performed by this routine assume that the variances of the logarithms of the values in the two groups are the same; in terms of raw (observed) values this implies a common coefficient of variation.
Common coefficient of variation (raw values): The standard deviation of either group divided by the mean of the group, where the standard deviation and the mean are given in observed, not logarithmically transformed values.
The values for the coefficient of variation of the two groups are assumed to be the same.
calculators.stat.ucla.edu /powercalc/normal/lognormal/help.php   (744 words)

  
 Aging Gray Wolves by Tooth Wear
Next, to compare the precision of the 4 biologists, we estimated the coefficient of variation for their estimates relative to the known ages.
We calculated individual coefficients of variation of the age estimate for each wolf, then averaged across wolves to produce a mean coefficient of variation for the reader (Campana et al.
An estimate of the coefficient of variation was expressed as the ratio of the standard deviation to the mean (Campana et al.
www.npwrc.usgs.gov /resource/mammals/toothage/methods.htm   (618 words)

  
 coefficient of relationship - Hutchinson encyclopedia article about coefficient of relationship   (Site not responding. Last check: 2007-11-06)
In certain species of insects (for example honey bees), females have only one set of chromosomes (inherited from the mother), so that sisters are identical in genetic make-up; this produces a different set of coefficients.
These coefficients are important in calculations of inclusive fitness.
This information should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional.
encyclopedia.farlex.com /Coefficient+of+relationship   (170 words)

  
 drip irrigation
The emitter flow variation that is determined from the emitter flow profile of the lateral line considers only the variation caused hydraulically and assumes that there is no emitter flow variation from the manufacturer.
It was found that the manufacturer's coefficient of variation of emitter flow for the single wall lateral line ranged from 0.04 to 0.08, with an overall average of 0.06, and the bi-wall lateral line ranged from 0.06 to 0.16, with an average figure of 0.11.
The effects of the manufacturers coefficient of variation of emitter flow on emitter flow variation can be determined from equation 7 or Figure 1, which is plotted from equation 7.
weather.nmsu.edu /dripdesign/coeffofvariation.htm   (915 words)

  
 Coefficient of Variation (CV) vs. Mean Interspike Interval (ISI) curves: . . . (ResearchIndex)
Coefficient of Variation (CV) vs. Mean Interspike Interval (ISI) curves:.
53 The variable discharge of cortical neurons: Implications for..
1 Coefficient of Variation of interspike intervals greater tha..
citeseer.ist.psu.edu /488699.html   (470 words)

  
 Coefficient of Variation   (Site not responding. Last check: 2007-11-06)
The coefficient of variation indicates how large the standard deviation is in relation to the mean.
If the data set is a sample, the coefficient of variation is computed as follows:
If the data set is a population, the coefficient of variation is computed as follows:
grail.cba.csuohio.edu /~popovich/oms/Ch03a/sld020.htm   (46 words)

  
 Inspection One - Providing inspection services to Relocation and Real Estate Professionals -
The coefficient of variation should not exceed 10 percent (1 sigma) at radon concentrations of 4 pCi/L or greater (U.S. EPA Measurement Protocols 1989).
The coefficient of variation (precision) should be monitored using the results of duplicate detectors.
The coefficient of variation should not exceed 20 percent (1 sigma) at radon concentrations of 4 pCi/L or greater (U.S. EPA Measurement Protocols 1989).
www.inspection1.com /types/radon.htm   (931 words)

  
 ELISA OPTIMISATION FOR MONITORING BACILLUS SUBTILIS IN PREHARVEST BIOCONTROL PROGRAMMES
A comparison of various incubation temperatures showed that the highest signal/background ratio was achieved at VC for 24 h and that the lowest standard coefficient of variation was observed when micrititer plate was baked under a heating lamp and fan (Table 1).
The coefficient of variation for the three fixatives were less than 10%.
Both 1% and 5% BSA concentrations gave the highest signal/background ratio and the coefficient of variation was also within acceptable limits.
www.avocadosource.com /WAC3/WAC3_p433.htm   (1610 words)

  
 KoreaMed - Basic Search   (Site not responding. Last check: 2007-11-06)
The coefficients of determination(r2) of 10 conversion equations ranged from 0.9996 to 0.9973(mean=0.9988) under 70kVp and 0.16 sec.
The coefficient of variation showed 0.11, 0.20 respectively at each copper step of 0.2, 0.1mm in thickness.
The Cu-Eq value and the coefficient of variation was 0.14+/-0.01mm and 0.07 at alveolar bone respectively.
www.koreamed.org /SearchBasic.php?RID=79440&DT=1&QY=%22J+Korean+Acad+Oral+Maxillofac++Radiol%22+%5BJTI%5D+AND+1999+%5BDPY%5D+AND+Feb+%5BDPM%5D   (228 words)

  
 Coefficient of Variation   (Site not responding. Last check: 2007-11-06)
Another measure to assess the variability of the throughput is the coefficient of variation (CoV).
It is defined as the standard deviation of a time series over the mean of the time series.
The coefficient of variation is dimensionless and independent of scale.
www.icsi.berkeley.edu /~widmer/tfrc/thesis/node60.html   (53 words)

  
 List of selected publications of Tom Snijders
It is argued that the proportional reduction in (estimated) variance components is not an attractive parameter to represent the joint importance of explanatory variables for modeling the dependent variable.
An approximation is derived to the covariance matrix of the estimators of the fixed regression coefficients (for variables at the lower and the higher level) under the assumption that the sample sizes at either level are large enough.
For three coefficients of similarity between pairs (dyads) of operational taxonomic units for multivariate binary data (presence/absence of attributes), parameters of their distribution under statistical independence are derived.
stat.gamma.rug.nl /snijders/publ.htm   (11250 words)

  
 Coefficient of variation: Facts and details from Encyclopedia Topic   (Site not responding. Last check: 2007-11-06)
(the coefficient of variation (CV) is a measure of dispersion of a probability distribution probability distribution quick summary:
The coefficient of variation is a dimensionless number that allows comparision of the variation of populations that have significantly different mean values.
It is often reported as on a scale of of 0-100 by multiplying the above calculation by 100.
www.absoluteastronomy.com /encyclopedia/c/co/coefficient_of_variation.htm   (198 words)

  
 Coefficient of Variation (CV)   (Site not responding. Last check: 2007-11-06)
The coefficient of variation is reported as a percentage and calculated from the average and standard deviation as follows:
For example, a CV of 3% means the standard deviation is equal to 3% of the average.
In this case, the CV is the best way to summarize the variation.
www.variation.com /cpa/help/hs114.htm   (86 words)

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