08 disclosure test
The P% Disclosure Test
In 2008, the 3-firm 80% rule will be augmented with an alternative algorithm that has been in use at the BLS National Office for some time. It is known as the P% test, but requires far more additional data to be collected. A P% test removes the largest and second largest U-I’s from the macro total. Then the remaining sum (third largest employer on down the line) is compared to the employment of the largest employer. If this tertiary employment exceeds P% of the largest U-I’s employment, then the aggregate will be disclosable. As an example, if there are 100 employees in a macro cell, 75 in the largest employer, 8 in the second largest, and 18 in all of the rest combined, then the cell will be disclosable if 18 / 75 > P%.
In the example listed here, the 18/75 value comes out to 24%. So, if P were set to 20%, the cell would be disclosed, but a 25% P would prevent disclosure. The P values are being closely guarded, and may not be revealed even after the method is put into effect. In order for this method to work, the macro data will need to be augmented so that both the largest and second largest U-I’s will be tracked for each macro cell. Due to these restrictions, the P% test will be conducted against summed micro data, rather against macro cells. This will ensure the highest level of reliability of disclosure testing results.
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