spearman’s rank correlation coefficient (SRCC), rs

• measures the strength of the correlation between 2 variables
• SRCC is always between -1 and 1.
• the closer the value is to 0, the weaker the correlation
• the further the value is from 0, the stronger the correlation
• If rs near 1, there is a strong positive correlation
• If rs = 0, there is zero correlation
• If rs near -1, there is a strong negative correlation.
• 𝑺𝑹𝑪𝑪, ��𝒔 = 𝟏 − 𝟔 ∑ 𝒅 �� 𝒏(𝒏𝟐 − 𝟏)

  Where d = difference between ranks

  n = number of values
• Calculating SRCC:

  1. Rank both sets of data (largest to smallest)

  2. Find the difference between each pair of ranks

  3. Square the differences

  4. Add the square of differences

  5. Find the value of n – count the number of pairs of data.

  6. Substitute into the formula – remember the 1 at the beginning.

  7. Interpret your SRCC value in terms of correlation and strength of correlation – make this in context of the question.