A tour of statistical techniques
(To the tune of: There's a hole in my bucket)
Me: I've done a correlation matrix (grid), using Pearson's correlation coefficient (r), for a selection of variables, using my statistical software SPSS.
Statistician: Yes, but having done that, some of the variables are not continuous, so you should use Spearman's correlation coefficient (rho).
Yes, but having said that, SPSS just uses Pearson's coefficient anyway, if the sample size is as large as this one.
Yes, but there are also some variables with few categories, so you ought to use Cramér's V instead.
Yes, but having done that, there are even some variables with only two values, and you should use the phi coefficient for them, it's simpler. And, to be consistent, you should turn all the variables into binary forms.
Yes, very good, but there's no need for that, because the phi coefficient for binary variables in 2x2 tables is just the same as the Pearson coefficient, which is easier to calculate. Oh, and SPSS will present the results as a nice grid, so why don't you use that instead...?