Cluster type

central value_z-score

(SiO₂)

central value_z-score

(PbO)

Class A composite glass

0.2681484506373271

−0.21377443548874983

Class B single lead glass

−1.0122076137090077

1.014815740759344

Class C single potassium glass

1.142025689829439

−1.2058295713283438