Generate 5 sets of samples from normal populations, each of size 10, on a spreadsheet software. Make sure that the mean and variance of each set can be modified easily.
Then compute
S S w = ∑ i = 1 m ∑ j = 1 n ( X i j − X ¯ i ⋅ ) 2 {\displaystyle SS_{w}=\sum _{i=1}^{m}\sum _{j=1}^{n}(X_{ij}-{\bar {X}}_{i\cdot })^{2}}