Spearman Rank-Order Correlation Coefficient

what type of test is Spearman Rank-Order Correlation Coefficient

nonparametric test

what is Spearman Rank-Order Correlation Coefficient used to identify

relationships or associations between two variables

what is Spearman Rank-Order Correlation Coefficient an adaptation of 

the Pearson product-moment correlation

when is spearman rank-order correlation coefficient calculated 

when the assumptions of the pearson analysis cannot be met 

what Spearman Rank-Order Correlation Coefficient used to analyze 

data that is ordinal level of measurement or scores measured at the

interval or ratio levels that are skewed or not normally distributed

for Spearman Rank-Order Correlation Coefficient what must each subject have 

a score (or value) on each of two variables, variable x and variable y

what must the scores be to conduct spearman rank

must be ranked

for spearman the scores in each variable are…

ranked separately

what are calculations of spearman based on

difference scores between a subject’s ranking on the first (variable x) and second (variable y) set of scores

Spearman Rank-Order Correlation Coefficient formula 

D=x-y

rho

statistic for the Spearman correlation coefficient

D

difference between the rankings of a subject’s score on both variables x and y

N

number of paired ranked scores

rho formula

spearman value range

-1 to +1 where a positive value indicated a positive relationship and a negative value indicates a negative or inverse relationship

for spearman whaat indicates the strongest relationship

Numbers closest to +1 or -1

what is rho statisitcal power

91%

what does rho having a statistical power of 91% mean

that the rho has a 9% smaller probability of detecting a relationship or association if one exists

for spearman if the sample size is greater than 50

the power of the rho is approximately equal to that of the Pearson r

strength of rho 

– <0.3 or <-0.3 – weak relationships

– 0.3 to 0.5 or -0.5 to -0.3 – moderate relationships

– 0.5 to 1.0 or -0.5 to -1.0 – strong relationships

– 0 = no relationship