Monday, November 28, 2016

Introduction to Link Analysis: Part 2 Association / Activity Matrix

I originally wrote this post for a software company’s blog in 2014. This company was bought out and recently their blog and website have been removed from the web permanently. I am reposting it here for posterity. 

Last week I started a series of posts on Link Analysis. Link Analysis diagrams are used to explain the relationships between entities in a criminal investigation. There are three main types of diagrams that are part of Link Analysis. They are:

  • Time Event Chart
  • Association / Activity Matrix
  • Link Analysis Diagram

Last week’s post focused on Time Event Charts. This post is going to cover the Association / Activity Matrix. One of the main uses of the Association / Activity Matrix is as a preparatory step in the creation of the Link Analysis Diagram. That’s not to say that it’s entirely useless by itself but you’ll rarely see it front and center in a Link Analysis presentation.

Association / Activity Matrix
Matrix analysis allows you to represent the relationship between persons, entities and/or events. Both the Association and Activity matrixes are similar in appearance.

An Association Matrix represents the relationships between persons and/or entities. There are two variations on the construction of an Association Matrix. The first has the names of the persons/entities along both the vertical and horizontal axis.



This type is the easiest to construct using a computer spreadsheet. The only caveat is that the names need to be in the same order along both axes in order to allow all possible combinations to be represented. This can make it more difficult to add persons to the matrix at a later time.

The other type is simpler to label as the labels only need to be entered once along the diagonal at the top of the diagram.



The easiest way to generate this second type is probably to photocopy or otherwise reproduce an existing blank chart form unless you are good with a drawing program.

Both types of diagram work the same way.



In this chart the relationship between Jones and Joe’s Bar is represented. Follow the column for Jones down to the row for Joe’s Bar.

There are a number of symbologies taught by various groups teaching link analysis. I am a firm believer that simpler is better. Rather than filling the matrix with a variety of symbols I believe the best method is to use this simple symbology:



As an investigator, it is your judgment that determines what a known association is and what is a suspected association. Representing suspected associations may assist you in determining potential areas for intelligence gathering activities or further investigation.

Activity Matrixes represent the relationship between persons and/or entities and events. Activity Matrixes work in nearly the same way. The main difference is that Activity Matrixes are constructed using a square or rectangular grid as opposed to a triangle grid.



You should normally label persons along the vertical axis and events, entities, locations, etc. along the horizontal axis. You do not need to have the same number of items on one axis as you do on the other.

An Activity Matrix is helpful in identifying key actors in a case. The more events a person is associated with, the more active that person is in your case. Some variations of both matrixes include a space to count the number of associations depicted for each person. Include a row along the bottom of your matrix and then count the number of associations in the column above that cell.

Next week, we’ll look at Link Analysis Diagrams.

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