Advanced Generic String Comparator (ua)

This comparison function is based on the standard uncertainty comparison function, u, with variants of Winkler/Lynch and McLaughlin. It has additional features to handle specific differences between fields, such as key punch and visual memory errors. Each feature makes use of the information made available from previous features. This comparison function takes no parameters. The following features are included in the advanced uncertainty function.

• The function determines each character in exact agreement and then assigns a value of 1.0 to each agreeing character. It then determines each disagreeing but similar character and assigns a value of 0.3 to each. Similar characters might occur because of scanning errors (for example, “1” the number versus “l” the letter) or keypunch errors (for example, “S” versus “D”).

• The function gives increased value to agreement on the beginning characters of a string. The algorithm adjusts the weighting value up by a fixed amount if the first four characters in each string agree; it adjusts the weighting value up by smaller value if only the first three, two, or one characters agree.

• The function adjusts the string comparison value if the strings are longer than six characters and more than half of the characters after the fourth character agree.