Cross-correlation of two random signals gives bimodal distribution

2000-10-30 Thread G. Anthony Reina
I'm having a problem concerning cross-correlation and was hoping someone could help explain. Here's what I'm doing: I create two random signals (each 100 points from gaussian distribution from -1 to 1) and find the maximum cross-correlation value (either negative or positive, whichever has the l

Re: Square root transformation

2000-05-23 Thread G. Anthony Reina
really too high of a value and was being biased (or artifically inflated) by the transform. That is what I was disputing. -Tony -- /// // G. Anthony Reina, MD // // The Neurosciences Institute // //

Re: Square root transformation

2000-05-23 Thread G. Anthony Reina
kind of smoke and mirrors, a "trick" that somehow makes the analysis flawed. In Sokal and Rohlf's Biometry (3rd ed., 1995), it gives a nice description of this on p. 411. -Tony -- /// // G. Anthony Reina

Re: Square root transformation

2000-05-23 Thread G. Anthony Reina
the same conclusions, but I'd really like to have a little more solid footing in the statistical theory of any biases I may be introducing. Thanks. -Tony -- /// // G. Anthony Reina, MD // // The Neurosciences Institute // // 1064

Square root transformation

2000-05-22 Thread G. Anthony Reina
eoretical merit? I can't see how this can be so. I thought that the square-root transform was a pretty sound way of reducing your chance of biasing the analysis if the data is non-normal (which most parametric tests require). Thanks. -Tony -- ///////

Correlation over time

2000-05-10 Thread G. Anthony Reina
I'm looking for a way to show how two continuous signals are correlated over time. In other words, if x(t) and y(t) are correlated signals (with some phase lag between them), does that correlation change over time? (and if so, then how does it vary) What I'd ideally like to get is something like

Significance of cross-correlation

2000-04-18 Thread G. Anthony Reina
I have two physiological signals (discharge rate of a neuron and electrical voltage [EMG] of a muscle). I'd like to determine the cross-correlation between the two signals as a function of time (i.e. if a "relationship" between the two signals exists, how does this "relationship" change over time)

Re: Bug in SPSS or SYSTAT regression ?

2000-02-25 Thread G. Anthony Reina
[EMAIL PROTECTED] wrote: > I have found a difference between the results produced by SPSS and > SYSTAT in linear regression with no constant term. Below are the > results from the programs. As you can see the adjusted R2 given by the > 2 programs is different. Which one is correct? > Quoting f