Question

Seven methods of teaching Economics in two universities are shown below. Calculate rank difference correlation.

Teaching Methods	I	II	III	IV	V	VI	VII
Rank of 'A's Students	2	1	5	3	4	7	6
Rank of 'B's Students	1	3	2	4	7	5	6

Answer 1

Teaching Methods	RA	RB	D = RA – RB	D2
I II III IV V VI VII	2 1 5 3 4 7 6	1 3 2 4 7 5 6	1 –2 3 –1 –3 2 0	1 4 9 1 9 4 0
				${\sum }_{}{D}^2=28$

N = 7
$$\begin{gathered} r_k=1-\frac{6{\sum }_{}{D}^2}{N^3-N} \\ \mathrm{or},r_k=1-\frac{6\times 28}{343-7}=\frac{336-168}{336}=0.5 \\ \mathrm{Hence},r_k=0.5 \end{gathered}$$