A measure of the degree of linear association among a pair of variables.

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9 views

Questionnaire data analysis. Correlation between a model and questionnaire data

kind of a newbie with data analysis here, and looking for some guidance. I've made a questionnaire in relation to a model regarding the security of certain software. The questionnaire is mostly made ...
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0answers
16 views

R Commander: how to test correlation across all variables? [on hold]

If I want to test correlation between two variables I would run the following command in R: ...
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0answers
9 views

Does it make sense for pairwise correlation to be uniformly higher than an ability?

I am fitting a graded response model to analyze a 16 item, 5 ordered response category scale. It shows univariate properties in an EFA with one very strong principal component. The distribution of ...
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21 views

calculating correlation that involves a variable calculated over a certain time period

My research is an education research. I administered a survey at time point 1 (TP1), 2 (TP2), and 3 (TP3). This is a likert-type survey, measures let's say Concept1 and Concept2. The sample size is ...
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1answer
27 views

Point-Biserial Correlation (r) for non homogeneous independent samples

I am performing an independent t-test, in which the independent variable is the "group" which has two values A and B representing an approach the participants used, and the dependent variable is a ...
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0answers
7 views

Correlation of data with varying trends

So I have a set of data that is not necessarily constantly increasing/decreasing relative to a parameter, but can show wave-like pattern, and even chaotic behaviours. Here are to examples, one ...
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0answers
12 views

How do I test the significance of my correlation coefficients for various NONLINEAR regressions?

I have a set of 25 points and I used a TI-84 calculator to calculate the linear, quadratic, logistic, exponential, and power regression models for this data set. I have, likewise, obtained the r^2 ...
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0answers
15 views

Using quantiles for correlation

Here's hoping that people don't get irritated if this was a repeat question, or perhaps not the best place to post this question -- I'm new to the community. My stats skills are basic, but I will ...
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0answers
29 views

The expected correlation from a mixture of binomial distribution

I am working on a particular mixture model of the following form: $\frac AB =\frac CD$, where I am mainly interested in the correlation between both ratios. I have done several simulations that show ...
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3answers
68 views

Express correlation matrix of $X$ in terms of $X^{T}X$ (in the OLS context)

In least squares estimation where $Y = \beta X$, how can we find the correlation matrix of $X$ in terms of $X^{T}X$? It seems that $X^{T}X$ is very close in structure to the correlation matrix, but ...
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2answers
359 views

Why does the correlation function in R, cor() return a matrix with fewer rows that you started with?

I have a matrix $G$ in which I would like to compute the correlation matrix of. The matrix in R looks like: ...
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0answers
7 views

Clustering correlated variables

I have a dataset with 10 variables. Three pairs of these variables are correlated. What happens if I add all of these variables in the clustering? Does this depend on the type of clustering? I found ...
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1answer
23 views

Minimum business sample required to do correlation analysis

I'm doing a bit of business analysis at division level for a company. I'm interested in determining if there is a relationship between engagement (and other people metrics) and financial performance ...
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0answers
12 views

What is way to measure relationship between independent categorical variable on dependent variable (categorical/continuous)? [duplicate]

If both dependent and independent are continuous then we can find correlation and we know which column can be more influential. But if independent variable is categorical, how will i know how much it ...
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0answers
30 views

about the relationship test! [closed]

Everyone! I have got some data about the soil property. And for the accury of data, we measured the same property three times ,and we checked some properties. So now I have a question. 1. Should I use ...
1
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2answers
45 views

Classifying time-series similarity - what variable should I train on?

I have ~10,000 time series, each with 65 time points. I'm interested in classifying each pair of time series as "similar" or "not similar". Here's an example of two similar (left) and not similar time ...
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0answers
16 views

Regression for continuous dependent variable with independent ordinal variable

My situation is as follows: as a teacher, I've given students the option to make 5 sets of homework during the year, which does not count for their grade, but solely to practice and receive feedback; ...
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0answers
19 views

Different R square calculation [closed]

how following R Square can be calculated from data? give me example in excel 1.Predicted 2.Adjusted 3.normal
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0answers
12 views

Time Series Sampling Effects on Correlation Estimation

I'm wondering what the effects of downsampling time series' can have on estimating their correlation and when this can be beneficial. More concretely, assume I have two time series $X_{t}$ and ...
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1answer
19 views

Figuring out causation from event data?

Suppose I have event data showing these things: users who signed up users who signed up and then went on to do main important activity users who signed up and then went on to invite a coworker ...
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0answers
10 views

Use DTW-approach for correlation coefficients

Dynamic time warping is a popular similarity metric which I use to find correlations between time series that have different length or are time shifted. As it is a similarity metric, it doesn't show ...
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0answers
15 views

Which test(s) can be used to capture a change in non-linear correlation over time?

Is there a test that can capture a change of correlation in a part of the dataset, i.e. year on year? Essentially I would like to understand and measure if the "local" correlation increases in a ...
0
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0answers
16 views

Ecological data analysis [closed]

How can I investigate environmental variables' (soil minerals and structure; plant richness, density, canopy cover, basal area; air and soil temperature, moisture) influence on macromycetes (diversity ...
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1answer
32 views

Correlation between fitted and observed values in linear model

This is abour linear model. How do I show/calculate the Correlation between the fitted values and observed values?
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0answers
5 views

Relationship/Correlation in this data set - does it exist?

Some analysis has been conducted for my business by an external company. The data, as it stands, only really tells part of the story and doesn't provide any real direction. The original study was ...
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0answers
16 views

How to identify crucial features that lead to a strong sports performance

I have a dataset (500 samples) that contains information about sportsmen. It contains about 30 features that describe: age body composition like weight and size amount of daily training ...
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0answers
11 views

SSCP vs correlation matrix [duplicate]

Lets say I have a matrix X, where each row is a subject and each column is a variable. I have a few questions about manipulating this matrix, and what the result is: If I calculate X'X, am I correct ...
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36 views

Sum of correlation coefficients

Assume I have given some information on three variables (time-series) which can be weighted and summed to build a proxy of the GDP (=g). The weights are given as $x_1, x_2$ and $x_3$. The correlation ...
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8 views

Generate random variables with predefined correlation structure AND fixing some values (followup)

This question is basically a followup to this one: Generate random variables with predefined correlation structure AND fixing some values because I can't follow the answer given there. I would like ...
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0answers
38 views

If my goal is to show very low correlation, how should I check for statistical significance?

I am working on a research project in social sciences. My null hypothesis is that there is a high correlation between two variables and my alternative hypothesis is that there is very low to no ...
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1answer
15 views

Comparing continuous data with categorical data (4 categories)?

I have a study examining the effect of high fat diet in rats. We have many continuous variable such as weight, inflammatory blood cytokine levels, insulin, etc. However the major change we have found ...
4
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2answers
58 views

Sample mean and variance independence in the case of correlated observations

Are the sample mean and sample variance of correlated normal observations independent? The classic theory relies on the independence of observations, but this is not the case. So as an example I ...
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0answers
32 views

correlation coefficient for exponential model - the perils of Excel

Editing a non-peer-reviewed paper I came across a Excel scatter-plot with an "exponential trend-line" drawn, AND the value of the correlation coefficient presented alongside (calculated for the ...
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0answers
17 views

Analysis and Processing of Time Series Data

My project requires me to accurately analyze several (15) financial time series data - Indicators. The data consist mostly of several variants of moving average and stochastic information (ie ...
3
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1answer
36 views

What does “significant rank correlation” mean in the context of Kendall Tau-B?

I am trying to understand how to correctly interpret "significant rank correlation" in the context of Kendall Tau-B. What can I conclude if the correlation is 1? The relationship is monotonic? Edit: ...
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26 views

When is it appropriate to use linear regression vs. Naive Bayes?

Based on my readings, it appears as though linear regression lends itself to cases where both X and Y are numerical and you have a large sample size, whereas Bayes is better for categorical variables ...
3
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1answer
97 views

What is the distribution of sample correlation coefficients between two uncorrelated normal variables?

I want to compare observed bivariate (Pearson's $\rho$ and Spearman's $\rho$) correlations coefficients with what would be expected from random data. Assume that we measure, say, 36, cases across ...
3
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1answer
43 views

Hypothesis testing for the (Pearson) correlation coefficient

I don't understand why we have to assume ρ=0 in to get the probability density function? If I say null hypothesis p is something like 0.3, I can still use the probability density function, can't I?
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0answers
18 views

Recommended Reading - Covariance & Correlation in R for Time Series [duplicate]

I'm at the beginnings of trying to find this out, and much of the reading out there is not quite what I'm looking for. I'm looking for recommended reading for determining correlation or covariance ...
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1answer
54 views

How to test if I can use cross-correlation?

I want to compare two time series in R and see if they are cross-correlated (with ccf). I believe that they have to be stationary? How that my data is stationary in R and are there any other ...
0
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1answer
20 views

Cross-correlation gives autocorrelation in R?

I am not very familiar with cross-correlation analysis. I am analysing a large number of "paired" time series. For each pair, I am doing a ccf in R. I read in other posts that the horizontal line ...
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1answer
37 views

Test if number of fish differ by location

I have a dataset which consists of location ID's (1 to 29 different locations) and each location has a couple of repeated measures (max n = 780, min n = 50). Each measurement consists of a number of ...
0
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1answer
32 views

Find a window of ‘best correlation’ – exploratory analysis

I have data from a neurobiological experiment and I'm interested in learning which parts of multiple time-series (e.g. event-related potentials) best explain behavioural data (e.g. accuracy). Rather ...
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0answers
10 views

Correcting for categorical differences in a correlation between descriptive groups and another variable

What I want to do it work out the effect of method of assessment on different students marks. So for example Module 1 has 70% exams. Students with qual type A got marks 1,2,3,6 while students with ...
1
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0answers
21 views

plotting a quasi-poisson regression

I have a quasi-poisson regression model for analysing the correlation between academic prestige and bulic visibility. I have a set of independent variables- continouse and dummies in this model. I ...
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1answer
30 views

What is the connection between many highly correlated parameters in weight matrix with gradient descent converges slowly?

I read this Do deep nets really need to be deep? paper. There is one line that seems important but I don't understand. In section 2.3, it is told that Because there are many highly correlated ...
3
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1answer
68 views

Correlated features in dataset

I undestand in general that it is important to take correlational structure into account while applying almost any statistical techniques. First question - could you help with the examples why it is ...
0
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1answer
34 views

Choosing a model for a relationship between academic prestige and public visibility

I have data frame in which I would like to analyse the correlation between academic prestige (factor analysis scores) and public visibility. These scatter plots reveal different patterns in the ...
3
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0answers
47 views

Is this “strong correlation” definition valid?

This page defines a a "strong correlation" using a formula that combines a standard correlation measure with lag-1 autocorrelation measures. I've never seen a definition of correlation like this ...
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1answer
57 views

Testing significance of cross-correlated series

I want to prove that, overall, signal B is correlated to signal A. I was thinking of using cross-correlation (in R) to measure this. Essentially I have two kinds of signals: signal A is a series of ...