SWK exact = 0.875446
SWK approx = 0.875204
PSSK exact = 0.0218669
PSSK approx = 0.0213766
LPWGK exact = 2.57351
LPWGK approx = 2.49102
GPWGK exact = 0.98783
GPWGK approx = 0.987591