About Master Indexes

The basic concept behind a Master Index system is to create single or master point within the database where you can go to find every reference to a specific person, vehicle, location or article of property. The manner in which this is accomplished can vary depending on how the software designers have chosen to implement the strategy. In fact this system design approach is widely debated as to its usefulness or practicality in an actual operational setting. Crimestar Corporation believes that properly implemented, the Master Index concept represents one of the most powerful tools in a law enforcement agency information arsenal.

However due to differing opinions on the impact vs. benefit of a Master Index, Crimestar Corporation has chosen to make the implementation of Master Indices very configurable.

Implementations of the Strategy

The Non Intervention Method

Some vendors create a Master Index by copying key information from every module into a Master File without any operator intervention. This file can then be searched resulting in a list of all references to a particular person, place or thing. While this tends to make these master files rather large, proponents of this approach argue that forcing operator intervention to "Match" or verify the information against data already in the system significantly degrades system performance and operator productivity.

An illustration of this approach could be represented as follows:

Index	Last Name	First Name	Middle Name	DOB	DL #	Module	Ref #
1	Smith	John	William	09/15/60	N123456	Accident	12345
2	Smith	John	William	09/15/60	N123456	Incident	23113
3	Smith	John	William	09/01/60	N123456	FI	94884
4	Smith	James	William	09/15/60	N123456	Cit	F12345

Notice that entry #3 shows the same last name, first name, middle name and Drivers License (DL) however has a different Date of Birth (DOB). Resolving the conflict that entry # 3 is likely the same person as reflected in entries 1,2 & 4 is not addressed. The assumption is that nobody really knows, therefor enter the data and move on, rather that attempting to resolve the issue. The problem here is that a subsequent search of John William Smith, DOB-09/15/60 will result in only 3 entries. Likewise a search on John William Smith will result in 4 entries and the user must evaluate each entry to ensure it is the person they are looking for.

The Intervention Matching Method

Other vendors have taken an explicit "Matching" approach, which forces the user to match the current record information with information in the Master Index to create a relational link. Then a short involvement index is updated to reflect the reason for the linkage. Proponents to this approach argue that while the process of explicit matching during the data entry process can be time consuming it forces a more consolidated and intelligent approach to the Master concept, and can create a more productive search result..

An illustration of this approach could be represented as follows:

MNI File

Index #	Last Name	First Name	Middle Name	DOB	DL #
1	Smith	John	William	09/15/60	N123456

Involvement entry file

Index #	Module	Ref #
1	Accident	12345
1	Incident	23113
1	FI	94884
1	Cit	F12345

Now when a search is performed for John William Smith DOB-09/15/60 the search only results in one entry. Representing that there is only one John William Smith with this DOB in the system. Then the Involvement entry file can be scanned to see everything that this individual has been known to be associated with.

Points to Remember

The above illustrations show only very basic data elements associated with an individual. The Master Name Index for example could have lots of other information associated with it, such as address, phone number, height, weight, hair color, eye color etc. In these circumstances where the number of data elements is significantly increased the resulting file size of the Non Intervention Method can become excessively large.

The significance and importance of this functional difference becomes even more apparent when the master indexes have thousands or hundreds of thousands of records. Likewise, every jurisdiction has chronic offenders, which keep showing up over and over. Having those persons history consolidated into a single master record is clearly convenient. With the Intervention Matching Method the record is designed to reflect the most recent or most current information. Remember each module detail record should hold the information as it is reflected on that particular document. This process ensures that each document can be reproduced even if the information is known to have changed.

CrimeStar’s Limited Intervention Method

Understanding the pros and cons of each of these indexing methods has led Crimestar Corporation to design a Limited Intervention Method. This method is designed to provide the organized structure and data normalization inherent to the Intervention Matching Method while attempting to eliminate or minimize the impact on system performance and operator productivity which is this methods biggest single drawback. When CrimeStar can match to a last name, first name and date of birth it will create the link without user intervention. However, if it can not automatically match to these data elements it will present the user with a summary list of possible entries, and permit the operator to manually make the ‘match’.

When a link is made to a master name record with a different name from the name listed in the source document, the name listed in the source document is added as an alias name to the linked master name index record.