Patent ID: 7818235

Claim:
A method for determining an estimate of at least one numerical attribute of at least one entity of a population of entities, in which the population changes and there are a limited number of observations on the at least one numerical attribute for the at least one entity, the method comprising: using a processor arrangement to determine a conditional index to track how a value of the at least one numerical attribute changes from one time to another for an entity, wherein the entity is a member of the population at both times; using the processor arrangement to determine an unconditional index representing an average level of the attribute for the entities that are in the population at a particular time; using the processor arrangement to estimate an attribute for at least one of each of the entities for which there is no actual attribute data; and displaying on a display a graphical-user-interface to display a data curve for the at least one entity based on the at least one numerical attribute, wherein the data curve includes numerical attributes determined using the conditional index and the unconditional index; wherein the determining of the conditional index for the particular time is performed by calculating a maximum likelihood estimator for the conditional index for the particular time, wherein an entity is considered if it satisfies the following conditions: (1) the entity is currently a member of the population of interest; and (2) the entity was a member of the population at the time of the most recent observation on the entity, and wherein the unconditional index is determined by averaging the attribute across both actual observations and estimated observations of the attribute that satisfy both of the conditions.