Questions tagged [variability]
Variability or dispersion describes how a variable's values are spread out or compressed.
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Testing for differences in water temperature variability of three sites
I believe this should be a very easy problem to solve but I can't seem to resolve this myself. I have water temperature data of three sites. Temperature was logged every 30 min for ca. 2 years. I am ...
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8 views
Assessing variability in a repeated measures study
I want to assess technical variability/dispersion between several same-subject measurements (i.e which groups have more variability):
My data consists of a set of cases (with age and sex variables) ...
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Test contribution of variability of one term on variability of residuals
I have a very simple calculation in which observed precipitation (PPT) minus observed evapotranspiration (ET) yields a residual term of Potential Infiltration and Runoff (PIR).
PIR = PPT - ET
Both ...
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34 views
Time series Variability
How to understand variabilty between output and input variable, can someone help me in understanding how mean, variance and sd will help in identifying relation between them.
I have added a glimpse ...
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What model to use to evaluate whether the “variability” of one variable is determined by the “variability” of other variables?
I have observations taken for four subjects at a number of points/locations. The data is formatted similarly to as below:
I am not directly interested in the impact that a predictor has on the ...
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130 views
What's the best method to measure relative variability for non normal data?
I have a set of data that states the volume required each month for the next 12 for 750 raw materials.
I would like to determine the variability in the demand for each material, and categorise the ...
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26 views
Measure for variability of proportional data
I have a list of expected values (E) for the proportions of 20 amino acids in protein sequences.In a particular set of protein sequences these proportions differ from the expected values. In a subset ...
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1answer
35 views
Understanding partial autocorrelation (PACF) and variability
A strong positive partial autocorrelation of lag 1 means that an observation is highly correlated with its previous observation whereas a near zero PACF indicates no correlation.
Does that mean that ...
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110 views
How to calculate the variability of proportions?
I need to find the proper sample size, and I have found formula in the Stanford lectures. But I can’t understand what the “variability” of proportions means in this case.
Consider two proportions :
...
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92 views
Confidence interval for population variance and chi-square distribution [closed]
At present, i am reading the e-book by Robert L. Mcdonald(Professor of Finance,Northwestern University's Kellogg school of Management) named $"Derivatives Markets" 3rd Edition.$ In that book, I didn'...
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3answers
158 views
Why we try to capture variability?
I am new to Statistics and I have a Mathematics background. In Statistics, particularly in Linear Regression and Principal Component Analysis (PCA) so far what I have understood is that the main idea ...
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13 views
How to test whether variability between subjects (repeated measures) is significant or not?
I have resting state fMRI data of 77 subjects. For each subject, there are (let's say) 10 regions of interest, and for each region, 50 measurements (time-series). I am trying to compare the ...
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Measuring relative variability for variables with different scales II
I'm reformulating this question to see if I might have better luck than OP did at encouraging a response.
Consider that you have two univariate datasets at different scales, and need to establish ...
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3answers
704 views
Ways of visually comparing variance of data [closed]
I have a dataset containing 8 categories, I now want to visually compare the variance between the categories. The most common approach would be to use box plots or violin plots but I would like to ...
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126 views
Variability of positive and negative values
I'm interested in variability of postural changes in blood pressure. From a lying to standing position, blood pressure can fall or rise. In my dataset, I have 4 measurements of postural changes over ...
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21 views
Maximum Possible Variation Ratio
When calculating the maximum possible variation ratio for a variable, what does k represent?
Bachman and Paternoster (2017, p. 107) define the variation ratio as:
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1answer
48 views
If we change only one value of a data set, will the mean absolute deviation behave in the same way as standard deviation?
I took the new data as b and the data removed as a and calculated the new mean and used that to find the new mean and deviation in terms of the old. But it gets too complicated and there is no way to ...
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1answer
15 views
what to say about low variability
I did a survey and 4-point likert scale and most of survey participants responded “Agree” or “Strongly Agree”
and that made low variability in the summated scale scores,
what can I write for the ...
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21 views
Variability in categorical variables while reducing dimensionality
If a dataset has a variable with categorical values (A, B, C, D, E, F), would converting them to numeric and breaking them down into separate columns (for example, column A that will have 1s for all ...
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26 views
Is there any universal criterion for small vs. large variability?
Is there any universal criterion that permits to say that there is small or large variability? For example, I plan to conduct an experiment. I would like to say that if obtain small variability, I ...
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29 views
How are mean results on benchmark obtained when training neural networks?
In most neural network papers, networks are trained on a known database where state-of-the-art performance is known ("benchmark"). Whatever metric is chosen to illustrate the network's performance, ...
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1answer
118 views
What problem or game are variance and standard deviation optimal solutions for?
For a given random variable (or a population, or a stochastic process), mathematical expectation is the answer to a question What point forecast minimizes the expected square loss?. Also, it is the ...
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19 views
Good metric for describing relative variation of data
I am measuring the energy consumption and runtime of computer programs and would like to select a subset of the programs that have stable energy / runtimes. Each program is ran 10 times and I measure ...
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52 views
Average variability of small data set
I have data for 300 devices and each device has been tested a different number of times so some devices have 2 data points and some have 8. For example, one device scored 5, 6.5, 6.5, 6, 6, 6 whilst ...
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42 views
Measuring how “changey” a time series is over time
I am currently working with a medical dataset which among other things contains data on usage of certain instruments as well as power levels. I am attempting to monitor how "fidgety" a care provider ...
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1answer
591 views
What can be used to evaluate “variance” of samples of categorical data?
Suppose you are drawing samples from a population of categorical variables. Given samples s1 and s2, I want to calculate an index that would tell me how close I am to the ideal situation where all ...
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22 views
Difference of variability and its significance
I am quite new to statistics and I am trying to interpret a result I found in a medical study. Specifically, I want to know what methods they used so I can reproduce those in an analysis of a study of ...
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344 views
comparing time-series variability
I have consecutive measurements of two different phenomena (x and y) on the same subject, giving me a collection of time-series x_ik(t) and y_ik(t), where i is the i-th measurement and k is the k-th ...
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50 views
Significance test on interobserver variability
I am pretty new to statistical testing.
So here is my (completely revised) problem:
I have n observers reading the same m datasets consisting of k parameters.
For every parameter $k_i$, I therefore ...
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1answer
524 views
Model stability and variability
I am using polynomial regression to predict mean occupancy in a hospital unit using average length of stay (LOS) and arrival rate to the unit. I am using different percentages of training sets to ...
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1answer
98 views
Comparing variability of measures across time
I am working with some data where I have measurements for two outputs (Output A and Output B) for 5 participants in an experiment. Each of the 5 participants have both their Output A and Output B ...
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1answer
1k views
Confidence Interval Widths as Measure for Variability
I would like to know to which degree the width of a confidence interval can be used as a measure of variability of a statistic.
For instance, the confidence interval for the mean is given by $[\bar{x}...
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2answers
69 views
Accounting for spatial clumping when determining the variability of a sample
I am looking for a way to account for the spatial clumping/clustering/ in my data.
My data comes from 50m line transects. For each transect I recorded the grass height at 2m intervals, giving me 25 ...
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1answer
76 views
measures of sequential variation
I have psychological data that consists of series of binary choices (e.g., 1001010101) made by research subjects, where 1 and 0 reflect two different options that can be chosen.
Are there any known ...
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52 views
Distance between distributions with emphasis on tail
I'm creating PDFs of rainfall observations, and I've got six years of data. I'm trying to see if small changes in some model parameters create PDFs that are significantly different than what I'd ...
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55 views
Assumptions on the Levene's test
I'm trying to conduct the Levene's test for 10 non-normal samples to study an eventual heteroscedasticity. I was trying to justify my applying of this test, but I can't find it's clear assumptions. ...
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1answer
206 views
When it is a good idea to average data to reduce variability?
I have 4 responses per day from animals, at different points of the day (morning, afternoon, etc).
My data is marred by a lot of variability, since the nature of the response is such that while some ...
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2answers
3k views
Interquartile range exceeds the median
What can one infer about the dispersion of a dataset when the interquartile range exceeds the median? Does this always indicate a large degree of variability? Are there any other summary statements of ...
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What type of statistical test can be used to compare multiple sets of data
I have attached a picture of my data plot to hopefully clarify what I'm trying to do. The data is pH adjustment of samples, the left most grouping is the pH curve of one set of samples with the ...
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199 views
How to compare coefficients of variation for lognormal data?
I want to compare the variability of two log-normal samples. They are being summarized as Coefficient of variations (CVs) and I want to test if one sample's CV is different from the other's.
To ...
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1answer
98 views
Pairwise distance as measure of variability
This is probably a naive question...
Why do we use something like standard deviation to measure variability, as opposed to something based on the difference between all pairs in a sample?
In other ...
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1answer
1k views
Variance/standard deviation versus interquartile range (IQR)
Variance and interquartile range (IQR) are both measures of variability.
But IQR is robust to outliers, whereas variance can be hugely affected by a single observation.
Since variance (or standard ...
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1answer
102 views
How to measure the variability of a set of sets?
I have a set of sets and I want to assign a measure of variability to it. If all member sets are the same (e.g., S0={{a,b},{a,b},{a,b}}), the measure shall be 0. If some members are different (e.g., ...
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Can the variability of this multi-variate categorical data set be computed?
I have a set of Survey responses in the format shown below. I want to provide a mathematical measure of Variability to show "how different" the population is, but I'm not sure how to do so without ...
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Is the variability index valid for the Pareto distribution
The Pareto distribution is defined from the CDF:
$$
F^{-1}(p) = \frac{b}{(1 − p)^{1/a}},\ 0 < p < 1,
$$
where, $b$ is the scale parameter and $a$ is the shape parameter.
In the Gaussian ...
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0answers
46 views
how to quantify variation in continuous outcome for samples matched on continuous predictor
I have a data consisting of about 2 million cases. Cases are scored on some (overdispersed) predictor we'll call "employee performance." I would like to match or pool cases with the same score or ...
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1answer
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Proportion of explained variability of a single level of a variable?
I have a dataset with one dependent variable and several independent categorical variables.
I want to explore the amount of variability each of the independent variables explain in the dependent ...
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Variability of the reference data and its effect on the transformed values
I conducted a study to compare two different tests at two different ages (children). Based on the previous literature we had hoped that the scores should be better (low score) with age but this was ...
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1answer
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What is the difference between standard error and margin of error and when to use which?
Will someone please explain what the difference is between standard error and margin of error and when to use which? I have not had luck finding a simple explanation on the differences anywhere on the ...
