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

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How to compare two matrices (A given matrix and a scaled up one)?

I have a matrix with 0.25 million rows and 50 columns. I have scaled up this matrix to 1.5 million rows and 50 columns using a Method A. I would like to measure the quality of the method I have ...
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1answer
32 views

Construct a correlation matrix based on pairwise correlation coefficients

For the purpose of simulation, I would like to construct such a correlation matrix that would respect to some extend the given set of preferable/desirable correlation coefficients for each pair of ...
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23 views

Controlling for categorical variables before correlation using residuals?

I’m looking for a way to control for the effect of multiple categorical variables, all of which contain two independent categories, on two continuous variables before I correlate these continuous ...
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1answer
46 views

Analyzing the effect of categorical variables on a correlation coefficient

For my research project, I’m looking for some help on how to analyze my data. The research setup is as follows: I’ve got two normal variables that I want to correlate with each other and a number of ...
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14 views

how one independent variable affects other variable in multiple regression

I have a two independent predictors in regression equation "X1" and "X2". X2 is categorical hence 1,0 is the allowed values. I have to find how X1 get affected based on value in X2 in following ...
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17 views

Correlation between non-independent variables

I want to conduct correlation between two variables, that have common term (difference scores). Originally there are three variables X, Y, Z. I want to conduct correlation between two variables that ...
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11 views

Correcting correlation for reliability and range restriction in both variables

I've been tasked with correcting a correlation coefficient for reliability and range restriction in both the predictor and the criterion, and I'm having no luck finding a formula that does this. The ...
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0answers
25 views

predicting hour of the day [on hold]

What would be a good model to use to predict hour of the day. For example, I'd like to predict hour of the day when a person will use transportation. sorry for not being clear! This is the header ...
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11 views

test of assocation for continuous IV, binary DV

What 'test of association' is appropriate when I have a series of IVs that are continuous and a DV that is binary (yes/no)? My research question: Which neuropsychological tests administered at Time 1 ...
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1answer
40 views

Algorithm to find subsets with high correlation

I have a reasonably large dataset (d) with predictor variables x1...xn and a target variable y. I can use recursive partitioning (such as CART or rpart in R) to find subsets of d with a high (or low) ...
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1answer
12 views

Testing correlation between multiscaled rank-ordered variables

I aim to test correlation for the following rank ordered ordinal variables : 1st set of variables - Total 4 ( These are reduced variables using PCA from original 10 variables to 4, ranked on a ...
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2answers
199 views

Absolute beginner needs help with correlation

I am very new to statistics, and have searched around the net and stack exchange for an answer, and have tried to guess how to deal with the problem. Therefore this post. I hope someone can help... I ...
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0answers
11 views

real time object tracking

I have correlation value of object using mean and standard deviation, now i want to normalized that correlation value. how can get normalized correlation in terms of percentage vale?
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21 views

In search of a proper similarity function

I'm trying to find the most similar sample between a candidate and a bag of samples. Consider you have a knowledge corpus as follows: ...
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1answer
20 views

Is there a way to estimate the distribution from only a small number of outliers?

For example, I was looking at this list of the 93 people who have broken the "10-second-barrier", after reading that sprinter Christophe Lemaitre was the first person of purely European decent to ...
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0answers
32 views

Quantity like correlation

I want to calculate this sort of quantity, $f()$, for my data. $x$ and $y$ are time series. $f$ behaves like a pseudo-correlation, but is different in the sense that even if the values jump up and ...
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38 views

Effect sizes in within-subject design on R

I'm doing a meta-analysis but I need your precious help on couple things : 1) First, on R, in the compute.es package, I found only effect sizes computation formula ...
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1answer
38 views

Similarity between [x,y,z] and [0,0,0]

I have two vectors $v_1$, $v_2$. Each can have arbitrary values and I measure their correlation. $v_1$ and $v_2$ can also be different in length and I zero-pad the shorter to macht the longer vector ...
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0answers
7 views

test multiple samples correlation

I have two samples with multiple variables. I compute pearson correlation coefficients between each variables pairs within each sample. How can I compare efficiently corresponding pearson coefficients ...
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3answers
67 views

Low $R^2$ value in social science or education research

I'm looking for paper(s) that talk about "why low $R^2$ value is acceptable in social science or education research". Please point me to the right journal if you know one.
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14 views

Non-independent correlation, jacknife on subjects?

I have an array of 12 subjects each of whom have 2 variables (i.e.right now I have 24 x 1 array..each subject repeated twice..). When I correlate this, I get a significant correlation. But because ...
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2answers
31 views

Pearson correlation test for non-gaussian data

I want to perform significance test for correlation coefficient. However my data is not normally distributed. In my books I have found tests only for the normally distributed data. Is there such test ...
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0answers
28 views

How to carry out correlation/significance analysis?

I am very new to statistics, and have searched around the net and stack exchange for an answer without luck. Therefore this post. I hope someone can help... I am carrying out an analysis of the ...
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0answers
22 views

How to interpret the regression slope of standardised variables

my y variable is crop production (in kg/ha) and x variable is rainfall (mm). In a linear regression, if the slope is 0.5. I would say, 'if rainfall increases by 1 mm yield increases by 0.5 kg/ha.' ...
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9answers
1k views

What is the relationship between $Y$ and $X$ in this plot?

What is the relationship between $Y$ and $X$ in the following plot? In my view there is negative linear relationship, But because we have a lot of outliers, the relationship is very weak. Am I right? ...
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21 views

Distribution of correlation coefficients for uniform random variables

Let $n>1$, let $X$ be uniformly distributed on $[-\frac12,\frac12]$, and consider the sequence $X_1,\ldots,X_{n+1}$ of independent copies of $X$. R implements ...
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11 views

Is there a way to correlate a variable with the shape of a series?

Given a collection of series, e.g. the nine depicted below, where each series has a rank associated with it, e.g. magenta is #1, orange is #2, black is #3, and so on, I'd like to find a ...
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0answers
60 views

Inference of Pearson's rho from distribution perturbation

I would like to infer the correlation between random variables $Q$ and $R$, however, I have access only to the distribution of $Q$ and the distribution of $P=Q+R$. We can see how Pearson's $\rho$ ...
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1answer
46 views

What does correlated data mean and how can I visualize it with scatterplot?

I'm playing around with the Abalone dataset in R and following along with this article. The dataset has 8 variables that are taken into account to predict the number of ...
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3answers
531 views

How do you interpret a significant but weak correlation?

I have carried out a number of Pearson Chi Square tests on the relationship between tail lesions and abscessation in pigs. I have found a significant (p = 0.005) but weak (Cramers V = 0.288) ...
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34 views

When are correlation coefficients and variances not enough?

I am reading a paper and found the following, Statistical uncertainties and dependencies are often measured by variances and correlation coefficients, but both uncertainty and dependence can be ...
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0answers
10 views

Correlation between several Likert type items

I want to examine the relationship between confirmation of the pre-purchase expectations with overall satisfaction, and then overall satisfaction with repurchase intention. confirmation of the ...
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0answers
16 views

Testing significance of a treatment inducing correlations over a time series

Example data In the example dataset, there are 3 distinct biological measurements, over 3 time points (0,12,24hrs) for 19 individuals. These individuals have been divided into 2 groups: treatment and ...
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9 views

Different Correlation/dependecy measures

I'm trying to figure what kind of correlation/depency measure to use on a multivariate data set I'm working on. I've tried the (pearson's)correlation, Kendall's Tau and Spearman's Rho. However, all ...
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1answer
36 views

why is the denominator of the correlation coefficient the SD of X multiplied by SD of Y?

I don't quite understand what is going on in the correlation coefficient formula. In the numerator we have the covariance, and in the denominator we have the standard deviation of variable x ...
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34 views

Testing correlation between two variables when there are other variables involved

I want to see if there is any correlation between number of pages in a paper and the citation it receives. If I just plot number of pages vs number of citations of a paper, I might get a correlation, ...
2
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2answers
151 views

How to test for a significant difference between several dependent correlation coefficients?

I have a group of correlation coefficients (more than two). They are all dependent on one variable A in the form of r_A1, r_A2, r_A3....r_Ak, where 1, 2 ...k denote other variables; they all have the ...
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0answers
13 views

Standardizing variables at item or index level: Does it make a difference?

I'm running some multiple group CFA models comparing covariance structure by race/ethnicity and have survey data from 6th, 8th, 10th and 12th graders. My supervisor has told me to combine 6th and 8th ...
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1answer
58 views

Is there a kind of random walk process for wich the reciprocal of the variance is a sum of reciprocals of variances of compound processes?

Context: The variance of a sum of independent random walks is a sum of their variances: $\sigma^2 = \sigma_1^2 + \sigma_2^2$. In case of a dependent random walks with bivariate normal distribution it ...
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1answer
33 views

Is the Spearman rank correlation matrix positive definite or not?

I've always believed that the Spearman rank correlation matrix doesn't need to be positive semidefinite because the correlations are estimated pairwise so there's always a chance that it may not be. ...
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1answer
39 views

Negative Weak Correlations

I've performed correlation tests and received negative weak correlations using ordinal and interval data. I've tired a log transformation, and still the correlations were the same. I'm looking for a ...
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21 views

Significance testing between two sets of Pearson's correlation coefficients

I have been reading through questions here to find an answer to my question but didn't find a satisfactory one. Here is my scenario: I have a system computing an algorithm on each of 100 units (so ...
2
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1answer
47 views

Drop highly correlated items?

I have two IVs that are highly correlated with each other at 0.979 (Pearson) & 0.919 (Kendall's). IV1: Quality of response IV2: Quality of Technical Advice Sample Size: 252 Considering the ...
3
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1answer
140 views

Why do we need $R^2$?

In linear regression, the $R^2$ value is the square of the correlation between predicted values and observed values. But why do we need the $R^2$ value? Why not just use the correlation coefficient? ...
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1answer
41 views

Probability of observing a false correlation and confidence limits

In oil and gas exploration/development it is common to use acustic impedance derived from reflection seismic surveys to predict the porosity measured in wells drilled in the reservoir. I often use ...
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0answers
20 views

Excel correlate nominal and quantitative

I have the following test data: How do I correlate the "believes" with "before" to determinate if it affects the "after"? When believes is set to 1 the "after" will be (randomly) higher than when ...
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0answers
25 views

which test should be used to detect the effect of one variable on another?

I have conducted a research on four independent groups of students; one experimental and one control group at two levels. The design of the study was like a pre-test and post-test. I want to detect ...
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1answer
21 views

Using Mantel to explore relationship between geographic distance and a multivariate character

I'm working with bird songs. A song is composed of many vocal parameters [highest frequency (Hz), lower frequency(Hz), bandwidth(Hz), duration (s), number of notes, and son on....] I'm interested in ...
0
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2answers
23 views

Correlations for nominal data

I have a gender variable in my questionnaire, I have done it where 1= Male and 2= Female. I would like to correlate this variable with their answers to compare the difference between male opinions ...
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0answers
21 views

Reporting Fixed Effects as (partial) correlations?

I'm doing a linear mixed effects analysis in which I'm really only interested in one of the fixed effects. I have several other fixed effects and a random intercept term, but none of them are ...