Match Rating Approach
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A phonetic algorithm developed by Western Airlines in 1977 for the indexation and comparison of homophonous names.
The algorithm itself has a simple set of encoding rules but a more lengthy set of comparison rules. The main mechanism being the similarity comparison which calculates the number of unmatched characters by comparing the strings from left to right and then from right to left and removing identical characters. This value is subtracted from 6 and then compared to a minimum threshold. The minimum threshold is defined by table A and is dependent upon the length of the strings.
The encoded name is known (perhaps incorrectly) as a Personal Numeric Identifier (PNI). The PNI codex can never contain more than 6 alpha only characters.
Match Rating Approach performs well with names containing the letter "y" unlike the original flavour of the NYSIIS algorithm. For example, the surnames "Smith" and "Smyth" are successfully matched.
MRA does not perform well with encoded names that differ in length by more than 2.
Contents |
[edit] Encoding Rules
- Delete all vowels unless the vowel begins the word
- Remove the second consonant of any double consonants present
- Reduce codex to 6 letters by joining the first 3 and last 3 letters only
[edit] Comparison Rules
- If the length difference between the strings is 3 or greater then no similarity comparison is done.
- Obtain the minimum rating value by calculating the length sum of the strings and using table A
- Process the name strings from left to right and remove any identical characters found from both names respectively.
- Process the unmatched strings from right to left and remove any identical characters found from both names respectively.
- Subtract 6 from the number of unmatched characters in the longer string. This is the similarity rating
- If the similarity rating equal to or greater than the minimum rating then the match is considered good.
[edit] Minimun Threshold
The following table shows the mapping between the minimum rating and the string lengths.
| Sum of Lengths | Minimum Rating |
|---|---|
| ≤ 4 | 5 |
| 4 < sum ≤ 7 | 4 |
| 7 < sum ≤ 11 | 3 |
| = 12 | 2 |
[edit] Match Rating Approach Examples
The table below displays the output of the match rating approach algorithm for some common homophonous names.
| Name | MRA Codex | Minimum Rating | Similarity Comparison Rating |
|---|---|---|---|
| Byrne | BYRN | 4 | 5 |
| Boern | BRN | 4 | 5 |
| Smith | SMTH | 3 | 5 |
| Smyth | SMYTH | 3 | 5 |
| Catherine | CTHRN | 3 | 4 |
| Kathryn | KTHRYN | 3 | 4 |
[edit] External References
An Overview of The Issues Related to the use of Personal Identifiers, HSMD, Statistics Canada
