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

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10 views

Assessing correlation/similarity in shape and position of two datasets

I have data-sets within which position and shape (curves, relative increase/decrease at any given x-value) are the defining characteristics, such as: And a simulation which attempts to recapture ...
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0answers
4 views

longitudinal correlations matrices (structural covariance)

I am interested in doing structural covariance analyses in a longitudinal manner. In structural covariance analyses in our field, we correlate grey matter volumes of various regions of the brain with ...
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0answers
17 views

Statistic test for correlation among multiple variables || statistical test for confirming sales pattern among multiple items

While thinking about sales of a company, I came across a question. I have data like below: Day1 day2 ......day30. item1 10. 20. ....... 30. ...
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12 views

Hashtag correlation [on hold]

What is the formula please to calculate the occurrence between 2 hashtags like in the hashtagify.me website please ?
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26 views

To perform the right Correlation test

I have a data.frame in R where head(data,3) gives ...
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32 views

Correlation between spatial distributions [on hold]

I would like some guidance on how best to approach the following: I have three spatial distributions (distance vs variable) each with the the same sampling interval but of different lengths ( so ...
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0answers
29 views

Correlation Coefficient and regression coefficient [on hold]

On analysing my data, the signs of the correlation and regression coefficients were different. what do i do to make them the same? on reading previous posts, some say the data must be normalised or ...
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15 views
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4 views

Multiple subgroups Linear Correlation

I would like to test the correlation between two devices. I have a set of measurements of both devices of a certain subject under different physiological conditions. And I have that over a batch of ...
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1answer
15 views

8 variables for 12 months. Sigmaplot

I have measeured 8 variables for 12 months. n = 5-20. So, now I have mean, STDEV, SEM and n for those variables. I have trying to show relationship within those variables and among months. So, I ...
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0answers
8 views

Statistical test between pairs of values recorded by human and machine inorder to find the agreement between them

I have a set of independent values (which are subjective) recorded based on both human observation and machine recorded ones. At this point I want to ask serval questions like what is the agreement ...
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17 views

What is the method i have to use to find correlation between multiple variables

I know how to find a correlation between 2 variables. How am i supposed to find correlations between multiple variables and how do i plot a graph for it?
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0answers
18 views

Bias of sample correlation for discrete distributions

Is there a proof showing the bias (or lack thereof) of the sample Pearson's correlation for discrete interval variables? In particular, I am interested in how such a proof handles the expected value ...
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3answers
46 views

Statistical analysis options on small datasets

first of all please excuse my poor knowledge of statistics I'm currently teaching myself and have no training in it. To test correlation I have created a data set that indicates by how much 5 cities ...
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14 views

Using likelihood for event correlation in Bayesian network

Assume we have a simple Bayesian network, each event (alarm propagation) is a binary vector. Each node can trigger an alarm independently, but alarm propagates in the network with the probabilities of ...
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0answers
11 views

Analyzing series of events, controlling lengths

(Excuse me for terminological problems. After I tried to find the solution, I started looking for at least the right names for the concepts I use, but I failed, as the simple descriptions I tried to ...
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0answers
17 views

Sample correlation matrix of discrete variables

Consider a population where each member is represented as a set of N correlated trinary variables (each coded as $\{-1, 0, 1\}$). I am trying to get an estimate of the mean of all elements in the ...
2
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0answers
38 views

What is my study design

I have two sample groups and I will not be manipulating the participants in any way so this is not an experimental design. However I wish to compare the results of the two samples (between subject ...
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2answers
71 views

Does zero correlation mean no causation? [duplicate]

If I demonstrated that there is no correlation between two random variables, does that mean that there is no cause and effect relation between them ?
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2answers
36 views

How to interpret R Pearson's correlation test?

I am trying to learn a bit of R and statistics so as "toy project" I have started from the famous Iris dataset (150 rows, 3 classes). I have applied to two features the "correlation test" in this way: ...
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1answer
34 views

Clear explanation of Cronbach's Alpha

I have difficulty in understanding Cronbach's Alpha's formula. I searched for google and StackExchange able to understand it. Even there are some topics trying to explain it intuitively, I could not ...
3
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1answer
28 views

Error term in multiple regression model

I am trying to run a multiple regression model to see the effect of field characteristics such as soil texture, slope and hydraulic conductivity on drainage density. My samples are agricultural ...
6
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2answers
64 views

Robustness of correlation test to non-normality

I'm trying to reconcile two seemingly opposite statements about robustness to non-normality of the Pearson's correlation test statistic (where the null means "no correlation"). This CV answer says: ...
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1answer
28 views

Pearson's r and what its value represents and how it varies?

this question was asked in Basic Statistics Course on Coursera website. What can you conclude about a Pearson's r that is bigger than 1? Options: The correlation is very high. This is impossible. ...
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0answers
21 views

How to see if 2 variables affect another variable?

I have a list of stocks with their % change, along with 2 other variables (Price Difference and Volume Difference). I would like to know how (if any) the variables Price Difference and Volume ...
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0answers
21 views

Correlation for cases of disease per year?

In my data set the y variable is the year (as in 2015 or 2016) and the x variable is the number of HIV cases. I want to do a simple correlation on this data set to see if HIV is increasing or ...
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0answers
5 views

Correlation between different variables with different relations [duplicate]

if x and y are positively correlated and x and z are negatively correlated. Is it implied that the relationship between x and y will be negative??(checked via pearson correlation)
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9 views

Interpreting the psych::cor.smoother function in R

I've tried to contact William Revelle (the package creator) about this but he isn't responding. In the psych package there is a function called cor.smoother, which determines whether or not a ...
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0answers
7 views

How is the weighted version of Kendall's Tau computed? And is there an implementation in R yet?

I could not find a satisfying answer to my question yet. Could someone maybe give me a very simple numerical example how the weighted version of Kendall's tau is calculated? Maybe for the following ...
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24 views

Correlation test over time

For my research I want to test whether the influence that certain variables have on compensation, have changed over time. The influence of this variables are measured by looking at the correlation. ...
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0answers
21 views

What is the minimum sample size require for regression and multiple regression with two independent variable and one dependent variable? [closed]

What is the minimum sample size require for regression and multiple regression with two independent variable and one dependent variable? I have two independent variable(weather & Seasonality ...
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0answers
12 views

Kruskal-Wallis across 3 groups non-significant, but regression of the same data very significant

I have an issue regarding the significance of an association that I can't seem to get my head around, because using one statistical test it is significant and using another, it is non-significant ...
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0answers
4 views

How can I build a gene regulation network with precision matrix?

Genes are assumed to follow a Multivariate Gaussian distribution, and the precision matrix is asked to estimated. However, after estimation, there are negative values in that matrix, what does that ...
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0answers
12 views

Sign of the correlation between endogenous/instrument variable and error term

I am doing my thesis using 2SLS, the IVs that I include to the model are not weak (F-stat>20), however, to prove that they are exogenous is a problem. I am going to use imperfect instrument approach ...
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0answers
15 views

hypothesis question [closed]

A sample of 15 individuals gave a sample correlation coefficient of r = 0.62. Carry out a hypothesis test of whether there is evidence of a significant increasing relationship between X and Y in the ...
3
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0answers
38 views

Correlation & Stationarity

In a purely historical or backward-looking, descriptive context, is it incorrect to naively compute the covariance $$ \mathbf{E}(XY) - \mathbf{E}(X)\mathbf{E}(Y) $$ and Pearson correlation coefficient ...
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18 views

correlation of two unequal spaced time series

I have two datasets. The nature of data is similar to time series but with exception that they are not using equal spacing between every two consecutive measurements. However the records on particular ...
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23 views

Efficient feature selection in regression analysis

It's a Deja Vu problem but I want to discuss in a computationally efficient perspective. Assuming I am running a ordinary linear regression, I have hundreds of factors features to choose from. I want ...
3
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1answer
34 views

Intuition for near-decorrelation through centering

Consider a $p\times 1$ random vector $\mathbf u = (u_1,...,u_p)'$ with zero mean vector and variance-covariance matrix $$E(\mathbf u \mathbf u')\equiv ...
2
votes
1answer
64 views

Correlation between two high frequency time series

I have two time series, both at a high-frequency level. My question has two parts: How do I calculate correlation in a high-frequency setting? I assume that the normal correlation theory would not ...
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0answers
23 views

Question: next step after regression analysis? how to tell if multiple variables all co-correlate?

I am new to regression analysis and I have found that my 'independent variable' or predictor correlates with several dependent variables (through multiple linear regression tests) in a way that ...
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0answers
6 views

Partial F test given Correlation matrix

How do I do a partial F test if the only information I have is number of observations and the correlation coefficient matrix? I read that the squared of the correlation coefficient is equal to $r^2$. ...
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0answers
12 views

What do we do with suppressor variables?

I have read about the suppression effect at below. Could anyone kindly help to direct what we do with it? Suppression effect in regression: definition and visual explanation/depiction More details: ...
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0answers
16 views

Moderated Correlation

I am interested in the moderation of a latent correlation. The model consists of two latent variables with three and four indicators. The latent variables are correlated and influenced by a continuous ...
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0answers
15 views

Regression problem (illogical signs on coefficients)

We are writing a thesis about the relation between CSR (Corporate Social Responsibility) and Return on Assets and are performing regression analysis in STATA to be able to analyze the results. Return ...
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0answers
13 views

Sample size for correlation study if r=0.39?

I am doing a correlation study. I need help in computing the sample size given the correlation coefficient of 0.39 with a power of 0.80 and alpha of 0.05? Thank you and hoping for answers.
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1answer
33 views

How can I combine nominal with ordinal data to build a unique variable?

I performed an Interview with 44 questions Protocol. The structure of questions is based on 18 variables. Major variables are coming from theory. Every major variable consists of 3,4 or more question ...
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0answers
12 views

Several variables in correlation matrix output

I'd like to improve a big correlation matrix output correla, because I want to see significante values (p<0.05) but with my code is very dificult to find ...
1
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0answers
17 views

What's the relationship between covariance, shared variance, and common variance?

I've generally assumed that shared variance and common variance were the same thing. However, here it is written that "Common variance is the realm of total collinearity. On the other hand, the term ...
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0answers
12 views

Comparing Self-Report Data to Binary results

I have two sets of data: DES scores (self-report) and whether dissociation was experienced during an experiment (yes or no). My sample size is 83 (71 no, 12 yes). I want to know if high DES scores are ...