2.1 Introduction

This section provides overview of the matching.

Each match rule defines a set of criteria, specified as comparisons, that the pair of records must satisfy in order to qualify as a match under that rule. The match rule also defines a decision to be applied to any records which satisfy the conditions of the rule. Most rules have a Review decision, meaning matches that hit the rule need to be reviewed. However, there are also elimination rules, where if the records being compared meet the rule’s criteria, a No Match decision is reached, and the two records will not be considered a match.

The rules are applied as a decision table, so if a pair of records qualifies as a match under a rule higher in the table, it will not be compared using any rules below that. All rules are configured to operate on a case-insensitive basis. Unless stated otherwise, all noise and whitespace characters are removed or normalized before matching.

Matches are generated based on a defined set of attributes for each rule. A weighted average of the score is generated for each of the attribute level matches.

There are two types of Matching services:
  • Real-Time Processing
  • Batch Processing

Note:

Source for this document means the customer dataset.

Target for this document means the watchlist.

In Real-Time processing, the values in the respective tags of candidate requests, are matched against a column in the target table. The screening application explicitly passes the strings as values in the request which forms “the strings to be matched” against “all the values in a column name”. Then, based on the matches received for the source string from search engine, the score and the feature vector for the matched strings (source and target) are generated. Scores which exceed the configured thresholds are taken and collected.

Table 2-1 Match Types Descriptions and Examples

Ruleset Name Description Example
Exact Considers two values and determines whether they match exactly. Applies only if Exact Match is selected. It does not apply when using Fuzzy Match. If the source attribute is “John smith” and target attribute is “John smith”, then the match is an exact match.
Character Edit Distance (CED) Considers two String tokens and determines how closely they match each other by calculating the minimum number of character edits (deletions, insertions and substitutions) needed to transform one value into the other.
For entities, stop words are not considered.
  • If the source attribute is “John smith” and target attribute is “Jon smith”, then the CED is 1 since the letter 'h' is missing between the source attribute and target attribute.
  • If the entity names are Oracle Financial Corporation and Finance Orcl Pvt. Ltd., then only Oracle Financial and Finance Orcl are considered for matching as corporation, Pvt., and Ltd. are stop words.

The CED for Orcl is 2 and CED for finance is 3, so the overall CED is 3.
Character Match Percentage (CMP) � Determines how closely two values match each other by calculating the Character Edit Distance between two String tokens and considering the length of the shorter of the two tokens, by character count. If the source attribute is “John smith” and target attribute is “Jon smith”, then the CMP is calculated using the formula (length of shorter string – CED) * 100 / length of longer string. In this case, it is (9-1) * 100/8 = 77.77%. �
Word Edit Distance (WED) Determines how well multi-word String values match each other by calculating the minimum number of word edits (word insertions, deletions and substitutions) required to transform one value to another.

If the source attribute is “John smith” and target attribute is “Jon smith”, then the WED is calculated by checking the number of words that did not match with the target words after allowing for character tolerance, which is the number of words in the source attribute that did not match the target attribute.

For example, the source string is Yohan Russel Smith and target string is Smith Johaan Rusel. First, we determine the CED for each word:
  • Yohan matches with Johann with a CED of 2.
  • Russel matches with Rusel with a CED of 1.
  • Smith matches with Smith with a CED of 0.
If we consider a character tolerance of 1, we can observe the following:
  • Russel with a character tolerance of 1 match with Rusel.
  • Smith with a character tolerance of 0 matches with Smith.
  • Yohan with a character tolerance of 2 does not match with Johann as the character tolerance is 1.

Based on these observations, we can conclude that one word does not match. This means that the WED is 1.
Word Match Percentage (WMP) Determines how closely, by percentage, two multi-word values match each other by calculating the Word Edit Distance between two Strings and taking into account the length of the longer or the shorter of the two values, by word count. The WMP is calculated using the formula (WMC/minimum word length) * 100. If the source attribute is “John smith” and target attribute is “Jon smith”, then the WMP is calculated as (2/5) * 100 = 40 %.
Word Match Count (WMC Determines how closely two multi-word values match each other by calculating the Word Edit Distance between two Strings and taking into account the length of the longer or the shorter of the two values, by word count. The WMC is like WED, with the difference being that WMC gives the number of matches between 2 words and WED gives the number of words that did not match between 2 words. If the source attribute is “John smith” and target attribute is “Jon smith”, then the WMC is 2 as two words have matched (allowing for the character tolerance).
Exact String Match Considers two String values and determines whether they match exactly.  
Abbreviation Checks if the first character matches with the first character of source and target values.  
Starts With Compares two values and determines whether either value starts with the whole of the other value. It therefore matches both exact matches and matches where one of the values starts the same as the other but contains extra information.  
Jaro Winkler or Reverse Jaro Winkler The Jaro Winkler similarity is the measure of the edit distance between two strings.  Click here for more information. In the Reverse Jaro Winkler, matches are generated even if the string is reversed. For example, if the source string is Mohammed Ali and the target string is Ali Mohammed, then the similarity = 1. If the source string is Mohammed Ali and the target string is Mohammed Ali, then the similarity = 1.
Levenshtein The Levenshtein Distance (LD) or edit distance provides the distance, or the number of edits (deletions, insertions, or substitutions) needed to transform the source string into the target string. Click here for more information. For example, if the source string is Mohamed and the target string is Mohammed, then the LD = 1, because there is one edit (insertion) required to match the source and target strings.