correlation

  1. L

    sampling/probability/correlation?

    I have in my course this problem do you have any idea from people who work daily with stats ? the question is like that: the following data are available concerning the products of a firm taken at random from four factories, and classified according to level of quality: Factory A : from low to...
  2. S

    Can you use correlation for percentages?

    I have two variables: the number of employees who work from home in the firm and the number of independent contractors in the firm - and I have this data for 70 firms. I am trying to determine what statistical measure of association I can use to determine whether there is a relationship...
  3. C

    Should I be using ANOVA?

    Hi, I haven't done statistics in just over a year so trying to read through old notes and feeling a bit stuck! I'm running an experiment looking at pitch discrimination in both isolated notes and melodies, comparing both musicians and non musicians. 1) measuring pitch: should I be using...
  4. J

    correlation between group/factor level & individual scores with group means and MSE

    Hi everyone, I've been working on this problem for a couple hours now, and I'm stumped. Essentially what we have are 4 groups of 25 people each. The groups are formed around a sales goal for each group ($10k, $20k, $30k, $40k). We don't know the individual scores within those groups, but...
  5. M

    Joint Probability

    Hi All, I'm currently in a grad course with a nice complement of stats which we have been tasked to learn ourselves. Having some difficulties understanding joint probabilities. Specifically, I have a problem where we have 3 possible outcomes with probabilities p1=0.4, p2=0.1 and p3=0.5. If we...
  6. P

    Test negative factors among correlated determinants

    Dear all, I am working on the obesity research. I found a molecule A that is negatively control the generation of adipocytes. I have a cohort of patients, and collected their adipose tissue samples (n=29). I do found that A is negatively correlated with adipogenesis in lean patients (n=22)...
  7. C

    associations and correlation VS Group differences

    Hello to all Talk Stats members! I would really appreciate your help on an issue that's really troubling me... In a previous post of mine I talked about the following likert type question I have in my questionnaire; "How would you evaluate new technologies in your life?" (1: entirely negative...
  8. M

    general correlation question

    hello! if variable A is correlated to var B (.37) and var B is correlated to var C (.32), can we infer the correlation between var A and var C? both correlations are p<0.01. is it .37 x .32? thanks!
  9. T

    Basic high school correlation coefficient help

    Question + info: http://i.imgur.com/iyBWi2i.png In question 3, the correlation coefficient I get is the exact same as in question 2... Therefore no improvement at all, what gives? For question 3, I just calculated sale price/sq foot and then took natural log (ln) for each value. So...
  10. E

    Correlation length

    Hi all, I'm working on a hydrological model. I supposed to build a mesh with correlation length in the permeability field. I know what is the meaning of the term 'Correlation length', It says that the permeability values that are near each other are relate and there is no drastic change in...
  11. H

    Should I use Pearson or Spearman correlation?

    I have to know whether two variables are correlated or not in a sample. None of them are normally distributed, so I assumed that I should run Spearman's correlation, which gave me a correlation coefficient of 0.392 (p<0.05, and Pearson's correlation was equally p<0.05). My problem is that now I...
  12. P

    Ordinal DV correlation analysis

    I am working on a project to analyze the frequency of use of public transit by an individual. However, One of my output variable "Frequency of use " is an ordinal scale with the 4 different categories: often, sometimes, rarely, never. I have treated this variable on a numerical scale with 1-...
  13. S

    Nominal & Ratio Variables: How to correlate?

    The following is the hypothesis I'm trying to work with: "Students who do not achieve at least 70% in high school English will not pass a college admissions test." I was given a dataset with over 800+ high school English grades expressed in percentages. The dataset also includes whether each...
  14. C

    Multiple Regression on SPSS - Correlations and Coefficients

    Sorry if this question sounds laughable to any of you. I'm really new to stats and find it quite challenging. I'm a 3rd year Biology student and am investigating the effect of several factors on the number of bats that pass the detector device each night. I have run a multiple linear...
  15. A

    Interpretation of a certain observation

    I have some identities that are distributed in a 2D space. Each identity has the properties X, Y, latitude, and longitude. Each dataset on average has 75 of these identities. For a particular dataset, when I plot X as a function of Y, I get no correlation. When I group the identities (say into...
  16. K

    Regression analysis in R - which variables to include?

    Hi all, I am doing causal research between the relation between a dependent variable Y which consists of 4 phases (so 4 dependent variables Y1, Y2, Y3 and Y4) and multiple independent variables X1, X2 and X3. My first step was checking if there were correlations between the Y and X...
  17. C

    Can I use ANOV for testing how correlation coefficient varies in condition??

    Hi everyone, I have a problem with the statistical analysis of my data namely I want to look into how anatomical values correlate with some electrophysiological ones, in different condition. Trying to simplify and explain, I want to relate the volume of some brain structures (a, b, c) to an...
  18. S

    Bootstrap procedure to test difference between correlation coefficients

    Hi everyone, I have two correlation coefficients (r1 and r2), obtained within the same sample (20 subjects). My aim is to test it they are significantly different. r1 is the correlation between a neurophysiological parameter and a behavioural parameter in condition A; r2 is the correlation...
  19. P

    Understanding correlations in order to test speed-accuracy trade-off in experiments

    I understand that in experiments where the measures of interest are speed (reaction time) and accuracy, for an effect to be valid one needs to make sure there is not a speed-accuracy trade-off (SAT). Namely, as reaction time gets quicker for a condition, accuracy should also be better for that...
  20. M

    Help with Correlation

    Hello! I need help for an issue i have. Let's assume that we have data of two variables (X and Y) for 14 different people. We can find the correlation between those two variables, for each one. In my case i find moderate correlation in some of them (which is also stat. significant), and for...