A measure of the degree of linear association among a pair of variables.
2
votes
1answer
23 views
Is the model wrong if a coefficient changes from minus in correlation table to plus in OLS?
Perhaps a very basic question but one that has me confused. Say, in a correlation table the relationship between A and the DV (...
0
votes
0answers
12 views
How to determine which Similarity measure to use when computing the robust gamma rank correlation coefficient?
I am interested in calculating the correlation between some expected and observed data. I am trying to compare observed (n<12) and expected values that are small proportions ranging from 0 to 7.4 ...
1
vote
0answers
29 views
Finding correlation between unequal group sizes in SPSS
I am working on correlating teacher factors with student achievement. How should I prepare the data set in SPSS for 130 teachers and 4000 student scores? I also have the same question with ...
0
votes
0answers
28 views
How to do correlation in MATLAB
I'm trying to do correlation between two .wav files or two .pcm files using MATLAB.
I just can't figure out how to do that! If anyone can help me I would appreciate it!
3
votes
0answers
76 views
Is Fisher overestimating the variance here?
[NB: the title of this post used to be "Please help me decipher Fisher on ANOVA". I've edited the question to make it more focused, and modified the title accordingly.]
Since anything written by R. ...
1
vote
0answers
52 views
Correlation between series of series
I want to study some data describing $k$ different systems. For a given system, these data can take two forms:
Global metric: a single value describing the whole system.
Local metric: a series of ...
3
votes
0answers
44 views
Generalised least squares: from regression coefficients to correlation coefficients?
For least squares with one predictor:
$y = \beta x + \epsilon$
If $x$ and $y$ are standardised prior to fitting (i.e. $\sim N(0,1)$), then:
$\beta$ is the same as the Pearson correlation ...
2
votes
2answers
60 views
Is partial correlation possible after Spearman's correlation?
I have two test groups that conducted an online task measuring response times (avg, avg(congruent), avg(incongruent)). I expected one group to be faster than the other but it turned out exactly the ...
2
votes
1answer
36 views
Assessing or comparing correlations at multiple locations
I have 10 independent locations (separated by at least 5 km) where I have collected abundance data for 17 species of birds. In particular, I want to look for correlations between one particular ...
1
vote
0answers
14 views
2 correlated variables , 2 conditions and 3 groups: what analysis?
In a design with two correlated dependent variable measures with similar range and variance, two within subject conditions and three diferent participant groups each tested at a diferent time point. ...
0
votes
0answers
38 views
Principal Component Analysis
I am a bit new to this. But I needed a clarification. I am creating a module in MATLAB that performs PCA on various data sets with varying number of explanatory and response variables. Depending on ...
2
votes
0answers
27 views
Finding correlations between aggregated and non aggregated data
I am trying to correlate server usage data with CPU utilization. E.g., X number of transactions on the server correlates with Y amount of CPU utilization. The transactions are reported hourly and ...
1
vote
0answers
38 views
Test of Difference between 2 Sets of Pearson Correlations
Suppose I have two sets of Pearson correlation coefficients -- call them set A & set B, and they are of the same size. How do I systematically compare the correlations in A against B? E.g., I want ...
7
votes
1answer
51 views
Generate covariance matrix with fixed values in certain cells
I want to be able to generate a covariance matrix of dimensions $D$ x $D$, such that certain specified cells of this matrix contain a fixed predetermined values (at least approximately).
For e.g. For ...
1
vote
0answers
21 views
Correlation in space (influence of building function on number of people passing through some point)
I am in a need of solving such problem: I have two data sets: number of people passing nearby some point in space (two points were analysed) and the function of buildings around those points. How do I ...
0
votes
0answers
39 views
How should I evaluate Correlation coefficient value
I am doing regression on a numeric dataset. This dataset is combined from 2 sources (one is from real-life data, one is from synthetic data). When I run cross-validation on this combined data, I get a ...
2
votes
3answers
54 views
How do you measure the likelihood of having a run?
I have some data that has runs of 0s with some 1s thrown in. For example:
000000000100000000010000000000000000000111111100000000
However, the 1s are much more ...
1
vote
0answers
46 views
What kind of model is this and how do you estimate its parameters?
$$T = A_0 + A_1M+ A_2M^2 + A_3\ln(P) + A_4\ln(P)^2+A_5M\ln(P)$$
where:
$T$ = Dependent variable
$P$ = Independent variable
$M$ = Independent variable
$A_0 \dots A_5$ = ...
3
votes
1answer
91 views
Validity of reporting correlation with N = 4
Experimental Design
4 Animals repeated a binary choice task with 60 trials over 15 days. For each day, we calculated the proportion for which the animal chose the given 'correct' stimulus. In ...
0
votes
0answers
27 views
How to determine canonical correspondence coefficients using PAST
I am trying to interpret axis 1 and axis 2 in terms of environmental variables while using PAST software for canonical correspondence analysis (detrended).
The output given does not provide ...
2
votes
0answers
29 views
Which test to use to compare vitamin D levels
I'm working on research into the vitamin D levels of professional and amateur soccer players, and relationship with factors such as skin color, vitamin D-intake etc.
I don't know which test to use. ...
-2
votes
0answers
35 views
What is the difference between simple, multiple, partial and canonical correlation?
What is the difference between simple, multiple, partial and canonical correlation? Could you provide simple examples with interpretations?
0
votes
2answers
57 views
Correlations of correlations using 3 data sets
I'm interested in how 14 environmental parameters co-vary with other environmental parameters and whether they show the same patterns in 3 regions. So 1st, I made a pairwise correlation table of the ...
7
votes
1answer
150 views
Can p-values for Pearson's correlation test be computed just from correlation coefficient and sample size?
Background: I read one article where authors report Pearson correlation 0.754 from sample size 878. Resulting p-value for correlation test is "two star" significant (i.e. p < 0.01).
However, I ...
0
votes
1answer
62 views
Correlation of Fixed Effects in lmer
I'm a psycholinguistics student with few knowledge in statistics and I have some doubts about a Correlation of Fixed Effects in lmer function (lme4 package). So, if my question is stupid… hummm… I'm ...
0
votes
0answers
41 views
What to watch out for when regressing Y on X when not only Y influences X but also X influences Y?
My data (about 20-30 data points) seems to be following a quadratic pattern, and it's quite plausible that they influence each other:
For $X < 16$, the influence (direction of "Granger-causality") ...
3
votes
1answer
70 views
How to compute the correlation coefficient between continuous and discrete variables ?
Is there any adjustment required when computing the correlation coefficient between:
continuous and discrete variable
two discrete variables ?
Thanks !
1
vote
0answers
51 views
How to algorithmically find plausible covariates at which to plot predicted responses?
I'm trying to plot the predictions of a linear model with multiple numeric predictors as a collection of plots such that $\hat Y$ is on the y-axis, each $X_j$ in turn is on the x-axis, and the ...
3
votes
0answers
49 views
Co-occurrence of properties in a population
I have 150 properties that may occur in a population of 10000 people. Individual people may have none, one or a couple of these properties. The properties are not mutually exclusive and have different ...
0
votes
0answers
55 views
Statistics problem travel distance [closed]
I've tried to solve this but I have no idea; I tried it several times but I still didn't manage to get a correct solution.
For a sample of 10 students, the following bivariate data represents the ...
5
votes
0answers
68 views
Is binning data valid prior to Pearson correlation?
Is it acceptable to bin data, calculate the mean of the bins, and then derive the Pearson correlation coefficient on the basis of these means? It seems a somewhat fishy procedure to me in that (if you ...
3
votes
1answer
43 views
Measuring Similarity of two Transient Signals
I am trying to measure the similarity between two signals, i.e. how identical they are.
A complete overlap (two lines forming a single line) should give me a value of 1, the greater the distance, ...
0
votes
1answer
38 views
Find the correlation between two binary observations when the parameter is one of two possible values with priors $p(\theta_1)$ and $p(\theta_2)$
Consider two binary observations, $x_1$ and $x_2$, which are independent given $\theta$. Now suppose there is uncertainty with respect to $\theta$. Find the correlation between two binary observations ...
2
votes
0answers
20 views
Choice of path weights in SEM conceptual model using openMx
I am reviewing the R package OpenMx for a genetic epidemiology analysis in order to learn how to specify and fit SEM models. I am new to this so bear with me. I am following the example on page 59 of ...
0
votes
1answer
68 views
Permutation test for multiple correlation test statistics
I read some great discussions about using permutation tests on correlation matrices to deal with Type I errors that arise from the multiple comparisons; however I have a question about the correlation ...
1
vote
2answers
47 views
Similarity between objects based on tags (binary features)
I have five millions of objects each of them having one or more tags. How do I compute statistically sound similarity score between each pair of the objects taking into account that:
There are 100 ...
0
votes
0answers
40 views
Comparing two models
I have data for the same response variable but measured in two different areas (Ra and Rb). I want to use the same explanatory data (E) to predict each response in turn:
Ra ~ E
then
Rb ~ E
I then ...
0
votes
0answers
61 views
Correlation, regression and causal modeling
This is probably a blindingly obvious answer for any seasoned statistician, but I am still confused as to how correlation differs to regression, technically.
I understand that one is a measure of ...
2
votes
2answers
72 views
How to check for a relationship between water bacterial levels
I have a set of data:
http://pastebin.com/KHLKD8XB
which is based on TVC (total viable counts - i.e., numbers of bacteria) from water going into a machine (BM), water taken from the machine (IM) ...
1
vote
0answers
27 views
How to manage correlation coefficients (Spearman, Kendall) with lists of different dimensions?
I have to compare two different lists of biomolecular annotations, and to find out their correlation degree.
To do this, I have implemented a function computing the Spearman's rank correlation ...
3
votes
1answer
96 views
Identifying a minimum time on web page as proxy for successful search outcome
Given a correlation between two sequences of numbers, I need to find to what point in one sequence the correlation is strongest. Here's why:
I'm tracking large numbers of pages in a knowledge base, ...
1
vote
0answers
21 views
Emulate correlation in loss data during aggregation
Hi this is my first post in stats,
I have n (~100) assets with loss data in R, each drawn from its own general pareto distribution.
Lets say I have 100 observations each, giving us a 100*100 ...
4
votes
0answers
33 views
How to model the distribution of a word game in order to find correlation between demographics and chosen words
I have an experiment (in the form of a word game) whereby people are asked to choose a set of words to describe associations with a topic with the aim of having another person guess the topic. I ...
0
votes
0answers
43 views
regression and correlation analysis [closed]
I. The main objective of regression analysis is to predict the dependent variable by the help of one or more independent variables.
II. The main objective of correlation analysis is to determine ...
1
vote
1answer
66 views
What is the best way of presenting a correlation? (in R)
I have two variables which show significant correlation (Spearman). I would like to graphically show the strength of the relationship, much like showing a linear regression fit with confidence bands. ...
2
votes
2answers
73 views
How do you explain 'co-integration' to determine spurious regression to a fairly new time series student?
I would appreciate it if someone could explain the concept of spurious regression intuitively / without it being too technical.
So far the student understands that spurious regression is basically ...
2
votes
0answers
62 views
Categorical vs Continuous Variable
I have two variables, one continuous and one categorical which I currently both use as predictor variables in a logistic regression model.
Their relationship is shown in the following plot with the ...
0
votes
2answers
62 views
Correlation vs measure of independence
So I have some data of which I'm looking at two different metrics, the first being "how sick a person is (higher = sicker)", and the second being "the presence of adverse events", and I've run 20 ...
-3
votes
1answer
73 views
Why are log transforms used in measuring dose-time association?
Explain why log(dose) and log(time) are used to measure the association between dose and time instead of the actual values of dose and time.
3
votes
0answers
38 views
Which variables are driving correlations within groups
I'm running an analysis on a few data sets that each typically have 100-200 cases measured across 120-160 variables - something similar to looking at gene expressions. Each variable is a non-centered ...
