DISC based profiling is widely used in recruitment. So widely used, in fact, that most applicants for any positions have taken one of the many DISC-based profiles several times. As with any test taken frequently, it is easy for candidates to learn the ‘preferred’ answers to the questions and hence manipulate their responses in order to look like the perfect candidate.
Most - Least Response Technique
Most DISC theory questionnaires utilize a forced-choice, one most-one least response technique. Consequently, it cuts in half the number of most-least comparisons that can be made, which impacts the reliability and validity of the questionnaire. The primary factors that affect the reliability of a test are the clarity of the test items and the length of the test. As a rule of thumb, the longer a test, the more reliable it tends to be. To avoid this, some DISC assessments now require respondent to rank the four items within each set (the scale is from 1 to 4, with 1 is "most" and 4 is "least"; each item represents one dimension). This response technique not only enhances the reliability and validity of the scales, but also generates profiles which are precise and explicitly defined.
Interdependence of the scales
Interdependence makes DISC an ipsative rather than normative test. Being ipsative, DISC profiles measure the relative strength of the four traits within one person not the strength of the traits in one person relative to that in other people.
For example, a very high Dominance score means the person is more interested in dominating than in influencing, submitting or complying. It does not mean the test candidate is a very dominant person relative to other people.
Moreover, in the selection stage, recruiters usually have to compare candidates against each other in order to pick out one that seems to be the best fit. A normal DISC assessment, which only provides graphs showing where a candidate is on each dimension, gives no ground for comparison. If companies and organizations want to use DISC to make better hiring decisions, it's better to find a DISC-based assessment with additional features that allow them to compare one candidate with another.
Source: Sales Team Focus & Profiles International