8. The method of claim 1 , wherein the merging of the date formats retains components of the date format for the first text string and components of the date format for the second text string that are not ambiguous.
1. A computer-implemented method for resolving ambiguities in date values associated with an attribute of an entity, the method comprising: at a computer system including one or more processors and memory storing one or more programs, the one or more processors executing the one or more programs to perform the operations of: obtaining a first text string associated with an attribute of an entity, wherein the first text string is extracted from a first web document; determining that the first text string conforms to one or more date formats; assigning a first confidence value for each of the date formats for the first text string based on a first number of unknown variables that remain when interpreting the first text string using each of the date formats; obtaining a second text string associated with the attribute of the entity, wherein the second text string is extracted from a second web document; determining that the second text string conforms to one or more of the date formats; assigning a second confidence value for each of the date formats for the second text string based on a second number of unknown variables that remain when interpreting the second text string using each of the date formats; determining a first date string expressed in a date format with a highest first confidence value for the first text string; determining a second date string expressed in a date format with a highest second confidence value for the second text string; and merging a first subset of the first date string and a second subset of the second date string to obtain a date value for the attribute.