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

learn more… | top users | synonyms

0
votes
1answer
21 views

Correlations within Factor in a pscyhometric instrument

I am working with results of a psychometric test. There are twelve factors and each have three subfactors. My problem is that one of the subfactors correlates very highly 0.3 to 0.7 with subfactors of ...
2
votes
2answers
55 views

mediator or moderator variable?

I have been given a set of data and I am confused as to whether one of the variables is a moderator or mediator variable. The hypothesis is that stress and well-being have an inverse relationship. ...
0
votes
0answers
10 views

How to interpret a rolling correlation?

The Dataset The table above contains hypothetical data about 2 vehicles. Vehicle 1 is following vehicle 2. The data is assumed to be collected every 0.1 seconds i.e. 1 frame is 0.1 seconds long. ...
1
vote
0answers
12 views

which statistic should I use for inter-rater agreement on nominal data, multiple responses

I have over 400 open-ended responses. The total has been coded by one rater, and a 10% identical sample of the total has been coded by 2 raters. There is a choice of 14 nominal codes, of which the ...
2
votes
3answers
50 views

Similarities and differences between correlation and regression

If I want to investigate how two continuous variables are linked, what is the difference between calculating the correlation coefficient (Pearson's r) versus calculating the (simple linear) regression ...
0
votes
2answers
40 views

Next steps after obtaining a significant Pearson coefficient

Lets say I have an R value of .5 and therefore an $R^2$ value of .25, and a p value < 0.001. (All through the stock cor.test function in R). Is there a way to isolate those cases/observations ...
0
votes
1answer
28 views

Getting all zero correlations,$\rho_{ij}=\frac{\mathbb cov(e_i,e_j)}{(V(e_i)V(e_j))^{1/2}}$

Consider the general regression model $$Y=X\beta+\epsilon$$ where, $Y$ is an $(n\times 1)$ vector of observations, $X$ is an $(n\times p)$ matrix of known form, $\beta$ is a $(p\times 1)$ vector ...
0
votes
0answers
11 views

Comparing two pearson coefficents w/ r^2

I have three variables, x,y, z. My sample n is about 17,000. My pearson coeficients & r^2: for x -> z it is 0.187, 0.034 for y -> z it's 0.311, 0.096 testing for significance, I receive a ...
2
votes
0answers
21 views

Pearson Correlation for Clustered data

I have a sample that was drawn using cluster sampling. Let say I have variables x and y, and I would like to check the significance of correlation between those two variables in SPSS 20 taking into ...
2
votes
1answer
54 views

Value of r, i.e. correlation coefficient, of data points on a horizontal straight line

1) If we use the formula $$r = \displaystyle \frac{\displaystyle\sum_{i=1}^n \left( x_i - \bar{x} \right) \left( y_i - \bar{y} \right)}{\sqrt{\displaystyle \sum_{i=1}^n \left( x_i - \bar{x}\right)^2 ...
0
votes
0answers
10 views

Difference between cross-correlations for two random variables and two probability functions.

Let me ask basic questions. Q1) What is the difference between cross-correlation between two random variables and cross-correlation between two probability functions for the two random variables? ...
0
votes
2answers
32 views

Correlation between unordered categorical variable and numerical variables

I have a dataframe with many observations and many variables. Some of them are categorical (unordered) and the others are numerical. I'm looking for associations between these variables. I've been ...
0
votes
0answers
19 views
3
votes
3answers
152 views

Correlation in linear regression

I once heard the following statements about the "correlation" in the context of regression. correlation only measures linear relationships $\text{corr}(X,Y)=0$ does not mean the variables are ...
2
votes
1answer
50 views

Interpret Pearsons correlation output from R

I have conducted Pearson's correlation in R and need help interpreting the results. ...
0
votes
2answers
44 views

Correlation analysis: Spearman's $\rho$ is significant, but Pearson's $r$ is not - with likert scale

I am doing a correlation analysis testing summated likert scales. However, one of the correlation analysis shows an unsignificant pearsons r (p = 0.068), BUT spearman's rho is 0.044. What should I ...
0
votes
0answers
47 views

If $X, Y$ are jointly standard normal with correlation $r$, and $a, b$ are constants, what is $p(Y < b | X < a)$?

The application here is interpreting the correlation coefficient $r$ in terms of $X$'s ability to predict $Y$ for extreme values of $X$. For example, if $r = .8$, then what is $p(Y < 0 | X < ...
2
votes
0answers
33 views

Correlation vs Partial Correlation to explore relationship in data

I have a cognitive architecture solving a set of tasks. Also I have data of human subjects solving the same set of tasks. Now I want to see whether I can find a relationship between the performance ...
1
vote
1answer
22 views

Using more measurements of lower quality or just the one with the best quality?

I am currently trying to analyze some pupillometry data. The device I use gives me X and Y measurements of the pupil area (from which I compute the total area via $A = \pi \times ...
1
vote
1answer
27 views

How can I determine if two features, given a set of data, are the same feature or not?

Thanks in advance for the help. Suppose I have a set of data of the form [feature, rating]. For the sake of argument lets assume feature can be movie A or movie B and rating is a ranked, continuous ...
2
votes
1answer
47 views

What is a good way of testing for a relationship between two count variables?

I have counts of occurrences of two types of words (A and B) in several texts. What I would like to test is whether the frequencies of occurrence of both types of words across texts is 'correlated'. ...
1
vote
0answers
29 views

Can the formula developed by Olkin und Siotani (1964) also be used to compare correlations from Spearman's $\rho$ and Cramér's $V$

The followgin formula is normally used for comparing two Pearsons $r$ correlations: Can this formula also be used to compare correlations from Spearman's $\rho$ and Cramér's $V$?
0
votes
0answers
28 views

Graduate research methods: what statistical test should I use?

I hope someone her can help me because I'm so lost. I'm trying to figure out what statistical test I should use for my study: I want to look at how promotions, stadium age, and environmental ...
0
votes
0answers
20 views

Correlation between independent variables in Generalized linear model

short intro: I wish to explain seedling abundance in a savanna ecosystem with two factors. one factor is 'canopy' which is either 0 (under a tree) or 1 (not under a tree). the other factor is distance ...
1
vote
0answers
11 views

Convolutional networks: how to deal with duplicate filters?

I have to train a convolutional network. When I visualize its conv filter matrices from a layer, many filters are quite similar, almost equal. 1) Don't you know a common way to detect couples of ...
4
votes
1answer
52 views

Interpretation of Spearman's rank correlation coefficient - beyond its significance

I calculated the Spearman's rank correlation coefficient interpretation for a given 2D dataset. I then tested its significance by doing a permutation test and obtained a p-value. I have a problem ...
0
votes
0answers
5 views

Comparing the means of correlations based on different size of sub-correlations

I would like to compare the mean correlation of two different sample groups: I had two groups of teachers who were judging their students' performance. One group of real teachers (N=10) judged on ...
0
votes
0answers
9 views

How to assess correlations of 3+ trials per observation?

I'm working with a set of 200 genes. For each gene, I have 3 p values representing independent evaluations of whether that gene shows differential expression under certain experimental conditions as ...
0
votes
0answers
9 views

Which method to find which features explain the target?

I have many categorical and numerical features and I sub-selected a few of them by a Random Forest. Now I'd like to determine which features probabilistically(/causally?) explain the target. Something ...
3
votes
1answer
53 views

What would be an effective strategy to correlate congressional attendance and precipitation?

I have data sets of the attendance of congresspeople, and of the weather in Washington, DC. I would like to examine whether and to what degree precipitation is correlated with the likelihood of ...
0
votes
0answers
14 views

Pearson Correlation with symmetric pairs?

I am correlating two features in the leaves of a dendrogram for a given tree distance (2,3,...). When i find the pair "A-B" at distance x I will also have the duplicate "B-A" in the same set for ...
1
vote
0answers
12 views

Using bootstrap to compare two ensemble correlations

I am asking for your help because I'm not sure whether the procedure I'm using is correct. I have two models, M1 and M2, and for each of them I have ten instances (ensemble members). For each model ...
6
votes
5answers
283 views

Is using deciles to find correlation a statistically valid approach?

I have a sample of 1,449 data points that are not correlated (r-squared 0.006). When analyzing the data, I discovered that by splitting the independent variable values into positive and negative ...
0
votes
0answers
22 views

Correlation tests – multivariate correlation matrix?

I just got comments from a reviewer to a submitted article and didn't understand what I should do very well. Here are the tests I performed: We first used principal components analysis (PCA) to ...
2
votes
2answers
48 views

How do you calculate the statistical significance of a correlation between $Y$ and $X$?

Can one just fit a linear model between $Y$ and $X$, and then take the p-values of the $t$-test done on the slope (or beta) of the linear model? Since presumably correlation would be in the same ...
0
votes
1answer
40 views

Differentiate two corelated variables

I am working on a prediction problem. I have a programming background and a small statistics one. If I have two dependent variables and one independent one, how do I work out if the two are ...
2
votes
2answers
73 views

Best transformation for sinuous data sets?

I am analysing annual behavioural patterns and am currently scratching my head over how to best transform data to test for correlation where my independent variable is the moon phase (given as ...
-1
votes
0answers
53 views

Finding correlations among many variables

I have 60 variables (each has 100 numerical data points) which could go up as high as 200 variables. I would like to run a test and see if there are any relationships between them. E.g, if variable A ...
4
votes
1answer
70 views

Proof of Point-Biserial Correlation being a special case of Pearson Correlation

I have been examining the use of the Point Biserial correlation as a statistic to measure the relationship between a dichotomous variable and a continuous one. Wikipedia et. al. seem to concur that ...
3
votes
0answers
35 views

Gibbs sampling for correlated random variables

Short summary Suppose two latent variables of a hierarchical model are correlated. Let $1-\epsilon$ be the degree of correlation. As $\epsilon\rightarrow 0$ the variables become perfectly correlated ...
5
votes
2answers
200 views

Why is a Pearson correlation of ranks valid despite normality assumption?

I am currently reading up on assumptions for Pearson correlations. An important assumption for the ensuing t-test seems to be that both variables come from normal distributions; if they don't, then ...
1
vote
1answer
32 views

Can I hypothesise an insignificant mediation? (Very basic stats)

This is for a simple psychology report. I was wondering if I could hypothesise an insignificant mediation. Eg: "...based on this research it is predicted that group identity is not a significant ...
0
votes
1answer
45 views

Interaction insignificant, main effects significant

I am using modprobe syntax on SPSS to test an interaction between narcissism and rumination on a dependent variable, aggression. I get a significant effect of rumination (b = .6450, t = 2.32, p = ...
0
votes
0answers
18 views

Which statistical tool do I apply to measure the association of Brand Identity and Brand Image?

I am pursuing my Ph.D. I am stuck with the last research objective. It talks about exploring the association of Brand Identity and Brand Image. Sample Size for measuring Brand Image (Customer ...
0
votes
0answers
24 views

How to collect related words with specified one?

Assume I have a word such as statistics, and research articles or text books about statistics. My question is how to detect top 100 related, highly associated ...
1
vote
0answers
39 views

Questions about G*Power

Since I found an insignificant result, I performed a power calculation in G*Power. But I am not entirely sure if I input the right number in some fields. My design is a 2(between Ss) x 2(between Ss) ...
1
vote
1answer
31 views

sum of correlation coefficients and correlation coefficient of product

Suppose that $X$, $Y$, and $W$ are random variables. Also consider the random variable $Z=XY$. I am interested in comparing the Pearson correlation coefficients $\rho(Z,W)$ to the correlation ...
1
vote
2answers
35 views

Multiple comparison on subgroups and overall comparison

I am trying to work out is there is any association between occurrence or not of an event in around 500 individuals and their randomised binary grouping (intervention vs placebo). However I also want ...
0
votes
1answer
31 views

Difference between skewed continuous variable and/ or ordinal variable by their binary group allocation

I need to select the most appropriate hypothesis test to answer: "whether there is any difference between variable 1 (ordinal) and/or variable 2 (continuous) by group (binary)". This is a randomised ...
0
votes
0answers
11 views

Comparing dependent correlations

I have a repeated measures data set with each subject ($N = 32$) being measured with two repeats of two tasks at two levels. My values of the correlation coefficient $r$ are: ...