1. An apparatus to determine a partial class membership of a data record in a class, the apparatus comprising: a record set acquisition module that receives a record set comprising a plurality of reference records, each reference record comprising a set of independent variables, each independent variable having an independent variable value, wherein each reference record of the record set comprises a same set of independent variables, wherein each reference record belongs to a known class within a group of classes; an unknown-class record receiving module that receives an unknown-class record, the unknown-class record comprising a set of independent variable values for the same set of independent variables as the independent variables of the reference records comprising the record set; a class identification module that creates a class vector for each reference record by setting a class identifier for the known class of the reference record to a first value and setting a class identifier for each class in the group of classes other than the known class of the reference record to a second value; a weighting module that calculates a set of unknown-class record weights for the unknown-class record according to a formula W=(R T R) −1 R T X wherein W comprises a vector of the unknown-class record weights, R comprises a matrix of the independent variable values for each reference record comprising the record set, and X comprises a vector containing the independent variable values of the unknown-class record, wherein R and X are transformed by scaling and shifting such that the formula W=(R T R) −1 R T X is accurate, the weighting module calculating a weight for each reference record in the record set, the set of unknown-class record weights calculated such that, when multiplied by the independent variable values of the reference records, a sum of the resultant values for each independent variable approximates each independent variable value in the set of independent variable values for the unknown-class record, each weight in the set of unknown-class record weights comprising a value greater than or equal to zero and less than or equal to one, wherein the sum of the set of unknown-class record weights approximates one; a classification module that simultaneously determines a partial class membership for the unknown-class record for each class in the group of classes by applying the class vectors created by the class identification module to the set of unknown-class record weights created by the weighting module, wherein each partial class membership identifies a probability that the unknown-class record belongs to a corresponding class in the group of classes, the classification module determining a partial class membership for each class in the group of classes, the partial class memberships comprising a value between zero and one; and wherein the record set acquisition module, unknown-class record receiving module, class identification module, weighting module, and classification module comprise one or more of logic hardware and executable code, the executable code stored on one or more non-transitory machine-readable storage media.