Sun Match Engine Matching Weight Formulation

The Sun Match Engine determines the matching weight between two records by comparing the match string fields between the two records using the rules defined in the match configuration file and taking into account the matching logic specified for each field. The Sun Match Engine can use either matching (m) and unmatching (u) conditional probabilities or agreement and disagreement weight ranges to fine-tune the match process. It uses the underlying algorithm to arrive at a match weight for each match string field. The weight generated for each field in the match string indicates the level of match between each field. The weights assigned to each field are then summed together for a total, composite matching weight between the two records. Agreement and disagreement weight ranges or m-probabilities and u-probabilities are defined in the match configuration file.

The following topics describe probabilities and weights.

• Matching and Unmatching Probabilities

• Agreement and Disagreement Weight Ranges

Matching and Unmatching Probabilities

When matching and unmatching conditional probabilities are used, the match engine uses a logarithmic formula to determine agreement and disagreement weights between fields. The m-probabilities and u-probabilities you specify determine the maximum agreement weight and minimum disagreement weight for each field, and so define the agreement and disagreement weight ranges for each field and for the entire record. These probabilities allow you to specify which fields provide the most reliable matching information and which provide the least. For example, in person matching, the gender field is not as reliable as the SSN field for determining a match since a person’s SSN is more specific. Therefore, the SSN field should have a higher m-probability than the gender field. The more reliable the field, the greater the m-probability for that field should be.

If a field matches between two records, an agreement weight, determined by the logarithmic formula using the m-probability and u-probability, is added to the composite match weight for the record. If the fields disagree, a disagreement weight is subtracted from the composite match weight. m-probabilities and u-probabilities are expressed as double values between one and zero (excluding one and zero) and can have up to 16 decimal points.

Agreement and Disagreement Weight Ranges

Defining agreement and disagreement weight ranges is a more direct way to implement m-probabilities and u-probabilities. Like probabilities, the maximum agreement and minimum disagreement weights you define for each field allow you to define the relative reliability of each field; however, the match weight has a more linear relationship with the numbers you specify. When you use agreement and disagreement weight ranges to determine the match weight, you define a maximum weight for each field when they are in complete agreement and a minimum weight for when they are in complete disagreement. The Sun Match Engine assigns a matching weight to each field that falls between the agreement and disagreement weights specified for the field. This provides a more convenient and intuitive representation of conditional probabilities.

Using the SSN and gender field example above, the SSN field would be assigned a higher maximum agreement weight and a lower minimum disagreement weight than the gender field because it is more reliable. If you assign a maximum agreement weight of “10” and two SSNs match, the match weight for that field is “10”. If you assign a minimum disagreement weight of “-10” and two SSNs are in complete disagreement, the match weight for that field is “-10”. Agreement and disagreement weights are expressed as double values and can have up to 16 decimal points.