The match rating approach (MRA) is a phonetic algorithm for indexing of words by their pronunciation developed by Western Airlines in 1977 for the indexation and comparison of homophonous names.[1]
The algorithm itself has a simple set of encoding rules but a more lengthy set of comparison rules.The main mechanism is 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 in 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 encoded name can never contain more than 6 alpha only characters.
The match rating approach performs well with names containing the letter "y", unlike the original flavor of the NYSIIS algorithm; for example, the surnames "Smith" and "Smyth" are successfully matched. However, MRA does not perform well with encoded names that differ in length by more than 2.
In this section, the words "string(s)" and "name(s)" mean "encoded string(s)" and "encoded name(s)".
The following table shows the mapping between the minimum rating and the string lengths.
≤ 4 | 5 | |
4 < sum ≤ 7 | 4 | |
7 < sum ≤ 11 | 3 | |
= 12 | 2 |
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 | ||
Smith | SMTH | 3 | 5 |
Smyth | SMYTH | ||
Catherine | CTHRN | 3 | 4 |
Kathryn | KTHRYN |