one of skw (Starkist water), cosw (Chicken of the sea water), pw (store–specific private label water), sko (Starkist oil), coso (Chicken of the sea oil)
price.z
price of brand z
Source
Kim, Byong–Do, Robert C. Blattberg and Peter E. Rossi (1995) “Modeling the distribution of price sensitivity and implications for optimal retail pricing”, Journal of Business Economics and Statistics, 13(3), 291.