Logarithmic Regression: Different correlation from 3 different calculators

[Dave Britten]

(06-09-2015 09:37 PM)groundbeef Wrote:  Just another data point for you - my Casio fx-9750GII gives 0.96837274.

It shows the regression results in a 10 character space, and I can't figure out how to get any more digits out of it.

Also, I'm sure you've checked this, but it took me three tries to get all the numbers entered correctly (and that's with the list display). When I had transposed the 2 and 7 in 58372, I got 0.96835999, pretty close to your TI-36X number.

And a question - I'm really weak in my stats knowledge, but is there any possible reason why more that 2 or maybe 3 significant figures for this value would matter? Of course, playing with numbers is its own fun.

Yeah, I've checked and rechecked the data several times to make sure everything is entered properly. If you want to get a few more digits out of it, this works on my fx-9860g Slim:

1. Evaluate r (from the Catalog) in Run mode.
2. Subtract the most significant digits from And and multiply by powers of 10 as needed.

With that method, the Casio gives me 0.968372745386438, even more digits than the TI or HP.

And in this particular case, you're right, I'm still getting more than enough accurate digits to draw a reasonable conclusion (i.e. that log regression isn't appropriate for this data). My fear is that the way I'm calculating correlation could have even worse accuracy with other datasets. If it were off in the hundredths place, that would be a bigger problem.