I'm making a project connected with identifying the dynamics of sales. My database concerns 26 weeks (so equally in 26 time-series observations) after launching the product, 126 time-series=126 different products.
I used clustering to group products with similar dynamics of sales. I applied two different approaches to pam() = k-medoids clustering. First one groupes time-series - 3 clusters, second one groupes S-curve parameters, counted before by curve fitting to each time-series - 6 clusters.
Now I would like to compare these two methods, but have no idea how to compare the quality of two clustering methods if I have different number of clusters.
I would be grateful for any suggestions.