Questions tagged [coefficient-of-variation]
A measure of dispersion expressed relative to the mean, used for positive variables. Equals the standard deviation divided by the mean.
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Distribution of true value when measurement imprecision is non-constant
What I believe to have understood so far
(I am not a mathematician or a statistician, so please correct me if I'm wrong.)
Say we are making measurements of some phenomenon $X$, and we have a normally ...
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Compare within subject variation between groups
I have run two experiments (exp). In each experiment, we have measured the same property in a number of subjects twice (V1 and V2). The number of subjects are different in the two experiments. and the ...
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coefficient of variation for a proportion
I'm new to the coefficient of variation. I'm trying to get at the precision of estimate. Using my software (Stata) I have an estimated percentage of 25% and a reported CV of 18. couple of questions:
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How can I quantify temporal variation into a single value without losing magnitude?
For my ecological research on the impacts of intensity of space-use on vegetation structure I need to quantify temporal variation in the intensity of space-use across years (resulting in a single ...
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what does it mean that the coefficient of variation equals 100%
I am taking a Probability and Statistics course. We know that:
coefficient of variation = (standard deviation / mean) * 100%
Geometrically, what does it mean that the coefficient of variation = 100%...
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A measure of variability/dispersion that captures only one direction of change
I am conducting a study trying to correlate changes in a biologic parameter (e.g., blood bilirubin concentration) with clinical outcomes (e.g., bleeding).
I have found that variability in such ...
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How can I get coefficient of variation (CoV) in R for linear mixed model analysing a RCBD
Hi everyone,
I have a linear mixed models (LMM) to analyse my RCBD.
is there a way to derive a coefficient of variation (CoV) in R for LMM? I have the mean estimates for each treatment (fixed effect) ...
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within and between subject variation for count data
I have count data from subjects measured 3 times by the same device (please see below). Each subject identified by "id" is measured at several timepoints "identified as "vnr" ...
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Risks for the Coefficient of Variation when using very skewed (log-transformed) data
I have many datasets which I have normalized using log-transformation, however for some datasets the log-transformation did not improve the skewness that good (still close to 1). For these datasets, I ...
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Modelling conditional coefficient of variation
Suppose we have 10,000 test tubes containing variable concentrations of some chemical. The aim is to use measurements of their chemical contents to characterise the measurement imprecision of a ...
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Differencing in coefficient of variation
For a project, I am trying to estimate the variability of an atmospheric variable across N years using the coefficient of variation. Let's call this the estimated ...
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Using the coefficient of variation to detect feature importance - but what if mean and sd are correlated? [closed]
I would like to have an estimate for the importance of a feature - the rough idea would be to define importance as the ratio between the mean and standard deviation. In other words, a feature is ...
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Interpreting coefficient of variation results [duplicate]
I am trying to interpret results for a question asking "which has the most variable abundances" so, I found the coefficient of variation in abundance of all species. Does it make sense to ...
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Comparison of Coefficients of Variation in paired groups via Bootstrap
I need to compare the variability of measures between two groups of observations. The observations are paired : the first group (G1) consists of observations made 12 years ago for 40 Belgian cities ...
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CV% with Close-End Formula
I am working with qPCR data, where the quantity of genetic material (in picograms) is the direct output of the machine. The quantity is then entered into a close end formula, which accounts for ...
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Explained variance score vs $R^2$ score
I came across explained variance score and $R^2$ score in scikit learn docs.
Docs defines exaplained variance score as:
$\text{explained variance} (y,\hat{y})=1-\frac{Var\{y-\bar{y}\}}{Var\{y\}}$
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what exactly does correlation mean [duplicate]
what exactly is a correlation of zero meant to be, does that mean that changes in x does not affect y, if that is the case, from the scatter plot
That is completely false, as sometimes as x increases,...
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Alternative for Coefficient of Variation as measure of reliability for grouped estimations
I have conducted a series of pairwise relatedness estimations. The resulting relatedness values can technically range from 0 to 1...
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Method of collecting and comparing outliers from sets of sets of populations
Background
I am a PhD student co-supervising a Master's student in our lab. I am mostly familiar with discrete mathematics, signal processing, and programming simulations. My statistics background ...
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Coefficient of variation of circular data
The definition of coefficient of variation is as follows:
coefficient of variation= standard deviation/mean.
I am using circular (directional) statistics to find the mean and standard deviation. My ...
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Coefficient of variation of log-Gamma distribution
If I have a Gamma distributed random variable $y$:
\begin{equation}
y \sim Gamma(\alpha, \beta)
\end{equation}
which has coefficient of variation $\frac{1}{\sqrt{\alpha}}$, then what would be the ...
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Coefficient of variation in a gamma location-scale mixed model
In ecology, location-scale mixed models are often used to extract the so-called 'coefficient of individual variation for predictability' (e.g. see, for instance, this paper), which is defined as the ...
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What is a good statistic to compare variation in percentages?
For my current project, I am interested in comparing groups of percentages.
For example, say that we would like to estimate the total number of customers in a month, when we are only a few weeks in.
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Coefficient of variation for exponential distribution: $\text{Var}(X)/E(X)^2$?
I am currently studying the textbook Modeling and Analysis of Stochastic Systems, third edition, by Kulkarni. Chapter 5.1 Exponential Distributions says the following:
The probability density ...
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If given the coefficeints, standard errors and r^2, how can I determine overall significance of an OLS model?
Basically the title. Say I am given coefficients 1,2,3 and standard errors .1, .02, .01 respectively and an R^2 value of 0.35. How would I go about testing the overall significance of the model?
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Can Coefficient of variation (CV) be used in non-normally distributed data?
I am trying to compare the variability of SpO2 values within a specific time frame from different patient groups. These values are non-normally distributed (negative skew). Is it still possible to use ...
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How much of the variation in X*Y is explained by the variation in X?
I would like to determine what percentage of the variation in XY is explained by the variation in X and Y individually. In other words, is there a metric of variation for which unknown_var_metric(XY) =...
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Proof of how to calculate the coefficient of variation of a nonlinear function
I'm struggling to find the proof of Eq. D.14b shown in the figure below:
The variable $b$ represents the “Least Squares” best-fit to the slope between $r_e$ and $r_t$ which both depend on $X_1$ to $...
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Rewriting coefficients of a regression
We are interested in the variable $\alpha_1$, in the equation
$
y_{iv1}=\alpha_0 + \alpha_1group_v+x_ia_x+ \gamma y_{iv0} + \epsilon_{iv1}
$
Where $y_{iv1}$ is a dummy variable, and $x_ia_x$ denotes ...
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Sample of rates: mean, standard deviation, coefficient of variation
A performance test of a software application measures the maximum rate (operations per second), which this application can handle. The test is repeated multiple times each iteration yielding the ...
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Comparison of Coefficients of Variation (CVs)
I have to compare the variability of measures between 2 groups (geographical regions).
Each group consists of a limited number of elements (i.e., the number of districts of each region); hence, a ...
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How to calculate coefficient of variation on cube or square root transformed data?
I transformed data to be normal using a cube root transformation. When I try to calculate the coefficient of variation I have tried back transforming the mean and sd (i.e., raise it to 3 "x^3&...
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Which variation estimate to prefer: SD, geomSD, CV?
I have a case where we see regional disparities in median received services. Services is a lognormally distributed variable. Plot is based on a lognormal model, examining y and sigma.
You can see that ...
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Decomposing the coefficient of variation into within- and between- group components
I know that the variance can be decomposed into within- and between-group components.
Let $Y$ be a vector and $Y_{i}$ and be a subgroup of $Y$ and we have $I$ subgroups, then
$Var_{T}(Y)=Var_{W}(Y)+...
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Error Propagation and CV?
I would like to know if someone can help me with basic statistical questions, please.
I read in many documents on the internet that if I want to calculate the mean of two values, where each value has ...
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Comparing coefficients of variation from numerous datasets
Question 1) Is it valid to calculate a coefficient of variation (CV) for each dataset if there is some spatial correlation in the datapoints?
I have 30 datasets. Each dataset is from an independent ...
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Reagent batch change, sample size, results significancy
We are working on a biological protocol measuring a patient's feature using a blood sample. This protocol has proven to have some variability (CV <= 10%).
During this process we sometime need to ...
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Confidence Intervals from Coefficient of Variation and mean
I apologize if the answer to this is obvious. Either 1) obviously not possible or 2) obviously simple.
I have an equation which gives 95% confidence interval lower bound (97.75%) of fatigue life ...
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Compare the variations of data between three groups
I have a data set of particle sizes of grains that are ground by three different machines. I want to test which machine is the best in grinding grains (i.e. the ground particles have the same sizes or ...
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Can I log-transform the sample variance estimated from an originally log-transformed data?
I have a dataset that is log-transformed to meet the assumptions of normality. I have estimated the mean and variance of each individual. I understand that the obtained mean is log-transformed. My ...
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How to separate the relationship between mean and standard deviation, mean and coefficient of variation?
I have again a similar question related to my previous posts. Please consider the following scenario:
Mean and standard deviation of A are positively correlated.
Mean and coefficient of variation (CV)...
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Is estimation of Coefficient of variation (CV) misleading when sample mean and standard deviation is negatively correlated?
I have a dataset with 145 individuals and two traits measured in 12 environments. I want to measure the variation among individuals i.e. individuals with high performance in one environment and low ...
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Is CV inflated when mean and standard deviation are negatively correlated?
I have two quantitative traits coming from 145 individuals x 12 environments combination. My goal is to correlate the specialization of each individual (trait 1) to the mean of each individual across ...
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Combined Coefficient of Variation
I am doing a research in 12 participants where I perform two different techniques three times each, at different moments. I would like to calculate the combined CV (Mean CV1 + CV2 + CV3), but I don't ...
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A variance measure for a variable that takes both positive and negative values with the mean close to zero
I've been using relative standard deviation as a measure of variance for my variables, but some of them take both positive and negative values and their mean is close to zero, so it's not a good ...
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Properties of CV (Coefficient of Variation) for the sum of normal random variables
Given two normally distributed random variable $X_1$ and $X_2$ given the mean and the variance to be $(\mu_1, \sigma_1)$ and $(\mu_2, \sigma_2)$ respectively, we know that the mean and standard ...
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Check which parameter causes less dispersion in a sample set - When to use CV (Coefficient of Variation) or CD (Coefficient of Dispersion) etc
The overall goal is to extract/engineer features from approximately 100 segments (various lengths but always more than 80 data points) that are as similar as possible to each other and have a very low ...
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Interpreting summary of mixed-effects model R (metafor)
I am a complete novice and was hoping for some clarity around interpretation of my results. Note the response ratio I am interested in is the log coefficient of variation ratio (lnCVR). Please see a ...
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Normalized statistical measure for agreement of biological replicates
I've conducted an experiment collecting samples from various depths in the ocean. At each depth, I collected 3 samples to act as biological replicates. I now want to show that all of my replicates ...
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A high variability in A is associated with outcome X : The use of the Coefficient of Variation to predict outcomes?
I want to know whether the Coefficient of Variation is a valid tool for the following problem:
The goal is to assess whether high variability in blood concentrations of a pharmaceutical drug is ...
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