In statistics, Spearman's rank correlation coefficient or Spearman's rho, named after Charles Spearman and often denoted by the Greek letter ρ (rho) or as r s , is a nonparametric measure of rank correlation (statistical dependence between the ranking of two variables). It assesses how well the relationship between two variables can be described using a monotonic function.

The Spearman correlation between two variables is equal to the Pearson correlation between the rank values of those two variables; while Pearson's correlation assesses linear relationships, Spearman's correlation assesses monotonic relationships (whether linear or not). If there are no repeated data values, a perfect Spearman correlation of +1 or −1 occurs when each of the variables is a perfect monotone function of the other.

Intuitively, the Spearman correlation between two variables will be high when observations have a similar (or identical for a correlation of 1) rank (i.e. relative position label of the observations within the variable: 1st, 2nd, 3rd, etc.) between the two variables, and low when observations have a dissimilar (or fully opposed for a correlation of -1) rank between the two variables.

Spearman's coefficient is appropriate for both continuous and discrete variables, including ordinal variables. Both Spearman's ρ and Kendall's τ tau can be formulated as special cases of a more general correlation coefficient.

Source : https://en.wikipedia.org/wiki/Spearman% ... oefficient

RJD007 wrote: Wed May 03, 2017 11:31 am Playing with spearman Full .ex4 not the 1.01 and when you enter a rank value below 10 the indicator shows 10 but when I do a icustom with a rank value of 5 I get a different value than with 10. which I would expect but still doesn't explain why the indicator only charts value of 10 or higher. The 1.01 only has the 4 types of averaging.