Multirelational k-Anonymity

In real life situations data is kept in multiple relational tables instead of single table. In relational tables, not all sensitive or identifying information is kept in each table separately. In this case k-anonymity may not be the best option. It may fail to ensure anonymity or cause too much distortion making data useless for data miners. Instead of running k-anonymity on each table separately, in Multirelational k-Anonymity tables are first joined together using some identifier that is common for each table.

For example suppose we have person specific table called Person, table called Diasese that contains list of diaseses and table called Job that lists jobs where people work. In these tables Id field is common for all three tables.

Person table

Id	First name	Last Name	Age	Gender	City
1	Juhan	Olev	33	Male	Elva
2	John	Smith	36	Male	Elva
3	Gebede	Ahmed	40	Male	Tartu

Diasese table

Id	Diasese
1	Flu
2	Hiv
3	Aids

Job table

Id	Job
1	Programmer
2	Analyst
3	Developer

In this example we can join tables using two rules: Person.Id = Diasese.id and Person.Id = Job.Id. These rule would give us the following table:

Id	First name	Last Name	Age	Gender	City	Diasese	Job
1	Juhan	Olev	33	Male	Elva	Flu	Programmer
2	John	Smith	36	Male	Elva	Hiv	Analyst
3	Gebede	Ahmed	40	Male	Tartu	Aids	Developer

Getting started

At left you have tables that you selected in previous step. Your task is to specify rules for joining these tables. To do this these steps:

1. Click on button Add rule. Now you should see that table headers have turned from gray to black an you can click on them.
2. Click on colum header in first table. The bacground color of selected header will become green. If you wish to change your selection, simply click on other header.
3. Click on matching colum header in second table. For example, if you clicked on Id column on Person table in previous step you might now want to click on Id column on Diasese table.
4. Click on button Ok to finish defining of rule after which you can see rule in purple box,
5. Repeat previous steps until you have specified rules for all the tables that you have listed on the left hand side.

Below the tables there is section called Preview of join which you can use to check if you have deined rules correctly. This table will be updated as you add or remove rules.

If you wish to remove the rule simply click on red X in rule box.

Once you have defined all the necessary rules, click on next button.