Rank Methods Spearman s
When the variables under consideration are not capable of quantitative measurement but can be arranged in serial order( ranks) we find correlation between the ranks of two series. This happens when we deal with qualitative characteristics such as honesty beauty etc. This method is called spearman rank difference methods or ranking methods and the correlation coefficient so obtained is called ranks correlation coefficient and is denoted by r_{s}. This methods was developed by Charles Edward spearman a British psychologist in 1904.