pearson's r

  1. R

    Point-biserial correlation when some of the test assumptions is violated

    Hi! I originally posted my question on StacExchange-CrossValidated, but no one there seems to be able to answer my question. This is the situation: I've got 15 raters who assess if there is deep invasion of a cancer type or not (dichotomous), and they can be either accurate or inaccurate...
  2. timtak

    Do clothes or underwear express character?

    Background I am a university level psychologists-come-English-conversation teacher, that directs student psychology even though I don't have much of a clue about stats. Generally I get my undergrad students to do a simple correlation research survey to test a hypothesis. We also use t-tests in...
  3. N

    Confidence Intervals for r: Why must we standardize?

    Hello! I know we are supposed to convert our r-values to z-values (and standard error) in order to calculate confidence intervals. I am a bit confused why we must do this. The sampling distribution for Pearson's r is a t-distribution and we use a t-crit in confidence intervals when our N...
  4. J

    Line of Best Fit and R Value contradict

    Hi, I'm fairly new to statistics and am wondering whether it is normal for the Line of Best fit and R value to contradict each other? As I was under the impression that the R value indicated the correlation coefficient. The Line of Best Fit on the graph indicates a negative correlation however...
  5. Y

    Is count data for parametric analysis or non-parametric analysis?

    Hi, In our paradigm, animals are presented with an stimulus and we count the number of calls they make. I believe the number of calls is discrete variable and count data. When we do an anlayis on these data, do we do parametric analysis or non-parametric analysis? For example, we...