"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 SpearmanÃ¢â‚¬â„¢s Rank Difference Method or Ranking Method and the correlation coefficient so obtained is called Rank Correlation Coefficient and is denoted by rs. This method was developed by Charles Edward Spearman, a British Psychologist in 1904. SpearmanÃ¢â‚¬â„¢s rank correlation coefficient is also used when the measurements are given for both the series.
However, SpearmanÃ¢â‚¬â„¢s rank correlation coefficient rs is nothing but Karl PearsonÃ¢â‚¬â„¢s correlation coefficient between the ranks, it can be interpreted in the same way as the Karl PearsonÃ¢â‚¬â„¢s correlation coefficient.
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