Table 1 Rating matrix data set with four users (rows) and three items (columns), with the rating of each user given in an ordinal scale of three points
User/ItemsI1I2I3
U1Embedded Image 2Embedded Image ?Embedded Image 3
U2Embedded Image 5Embedded Image 2Embedded Image ?
U3Embedded Image 3Embedded Image 3Embedded Image 1
U4Embedded Image ?Embedded Image 2Embedded Image 2
  • ? denotes missing values that need to be predicted.