correlation

  1. B

    Simulating correlated lifetimes at pre-specified correlation level

    I am trying to simulate remission times for 100 patients from an exponential distribution with mean 1 year. I also want to simulate after-remission times for these 100 patients. But it is very much likely in the real life scenario that those who remit quickly are likely to have comparatively...
  2. J

    Comparing Correlation Coefficients

    I currently work in the field of imaging. My question is in regards to comparing correlation coefficients. I have two image sets (which have an attached correlation coefficient) one has n1 number of image slices and the other has n2 number of image slices where n1 is not equal to n2. I...
  3. T

    Correlation and range

    Background: I am working on this project that examines the relationship between battery life and several variables. However my specific question pertains to the variable of the temperature of the environment they are in. I have 44 different batteries as my sample size. Their lifespan (in...
  4. S

    Generalised least squares: from regression coefficients to correlation coefficients?

    Hi All, I asked this on Stack Exchange, but it seems no-one there knows the answer. I wonder if anyone on talkstats can shed some light on it. 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...
  5. J

    Rank correlation - Comparing multiple sets of ranked metric values

    Rank correlation - Comparing multiple sets of ranked metric values First, I would like to thank the mods and experts who maintain and answer questions on this forum. Second, I really appreciate the fact that you reply to people who place "Please Help ME!!" in the subject line despite the fact...
  6. S

    Correlation

    I have a number of studies I am looking at and trying to compare their correlation coefficients ... esentially do a meta-analysis of correlation coefficients. I have been using Practical Meta-analysis by Lipsey and Wilson, but have not made much progress. I've also found some online resources...
  7. C

    Correlation not reflecting actual similarity of values

    Hello, I have 2 vector of data which correspond to rating in a test. Subjects perform the test and rate their result (from 0 to 10) and the next week they repeat the same procedure. The values are "very similar" but correlation does no actually reflect it. Since all values are around 8...
  8. V

    Estimating parameter from conditionals of non-independent data

    The context of this problem is the estimation of the distribution of a parameter v given sets of data A and B, where A and B are not independent. Suppose I know P(v | A) and P(v | B). Both of these distributions are definitely not normal (the answer should not make any assumptions about the...
  9. M

    Problems with graphing dinamic correlation after"mgarch dcc"

    Problems with graphing Hi everybody, I have some problems after having done the command "mgarch dcc.." and "predict H*, variance". I need to estimate and then graph the correlation so I generate a new variable with the one I have from the garch model. (Es. I want correlation between stocks...
  10. T

    [Parametric/Non-Parametric Correlation] - Which should be used?

    I have a data set consisting of waist size (cm) and weight (kg) of a group of people. I am looking to see if the two variables are related, and I assume a correlation test is the method I should be using (I apologise - I'm very new to SPSS and stat analysis in general). I understand that the...
  11. R

    Which subset of characters follow fairly linear relationship ?

    ALPHA and BETA are two physical quantities: A is dependent variable (Y-Axis) and B is independent variable (X-Axis). Values of ALPHA range from 50 to 250. (with steps of 50 i.e. 50, 100, 150, 200, 250 ) Values of BETA range from -2 to 3. (with steps of 1 i.e. -2, -1, 0, 1, 2, 3)...
  12. C

    finding the effect of X on the relationship between Y and Z

    I had a huge explanation and it got deleted, so here's a briefer version: I'm trying to find whether high trait empathy predicts a greater effect of self-other differences in status on state empathy and helping. I have differences coded as -1/1 (diff/sim). In the zero-order...
  13. H

    Relative size of a p-value for a second hypothesis, compared to the first.

    Hi all, I apologise in advance if this is a very easy question - I may be struggling with the wording, or I might just be a bit slow. The obtained p value for a correlation analysis is .036 where n = 50. If an analysis had been undertaken with n = 90, and the same sample correlation value was...
  14. A

    Why does a larger sample size produce a smaller p-value?

    Hi, I need help with this problem... The obtained p value for a correlation analysis is .036, for a sample size is 50. If the analysis had been undertaken with n = 90, and the same sample correlation value was again observed, what would be the relative size of the p value for the second...
  15. X

    Find correlation when SD and mean are given

    A guy got 88 in his test which has mean score of 64 with SD 8. He missed the second exam in which the meanscore was 45 and SD was 5. He got a prorated marks of 55. The prof used regression to get his second test marks. What was the corelation between 2 exams ? P.S: I would really appreciate...
  16. G

    Correlations among responses to a forced-choice scale

    I have data from participants who rate emotional content of pictures. Specifically, people see 20 pictures of abstract paintings (one at a time) and are asked, "what emotions is expressed in the picture?" There are 5 response options: anger, fear, sadness, happiness, and none. The key info here...
  17. I

    setting parameters in G*power for correlation tests

    Hello, everyone :) Need your help on how to set parameters in G*power... I am doing two very simple tests: one on pearson correlation between midterm scores and quiz another one on partial correlation between the same scores with motivation score as controlling variable. I need to run a...
  18. B

    Online-estimate of squared correlation coefficient for linear optimization

    Summary: Is there a way to directly estimate the squared correlation between two zero-mean Gaussian variables on-line and without storing more than two samples at any given time? Dear all, I am working on an optimization procedure to minimize the correlation between two zero-mean normally...
  19. T

    Correlation and significance with dependent observations

    Hi, I am trying to correlate two variables of which one variable has dependent observations as it is data derived from a social network. I am intending to use Spearman's rank correlation coefficient. As I understand conventional methods for significance test do not provide reliable results...