One question that the Birkman Research and Development Department receives is “Is The Birkman Method (TBM) an ipsative or normative measure?”
The short answer is “TBM is both ipsative and normative”. The long answer is “TBM is a mixture of ipsative and normative measures.” Underlying Need scales are normative with a ‘typical’ reference group. Usual Behavior scales are normative with an ‘atypical’ reference group (i.e., Need scale norms). Occupational Interest scales are ipsative and normative with a ‘typical’ reference group. Of course, Stress Behaviors are neither. Stress Behaviors are not calculated scales but rather derived directions of stress for each underlying psychosocial construct based on Usual-Need patterns. The intensity of the Stress Behavior is not measured. TBM only predicts the direction, while the Stress intensity varies based on many factors from situation to situation.
So why does the TBM have both ipsative and normative measures? Because both types of measures have strengths and weaknesses; thus, Dr. Roger Birkman used them in a complementary fashion to achieve an assessment that maximized the strengths and minimized the weaknesses of both types. The following paragraphs will define these two psychometric terms and provide their respective strengths and weaknesses.
In general, two types of personality and attitudinal measures exist: ipsative and normative. Normative measures allow for intra-individual and inter-individual difference comparisons; whereas, ipsative measures only allow for intra-individual differences comparisons. Normative measurement is popular and prominent in the United States, and ipsative measurement is utilized to more of an extent in Europe and Asia.
Ipsative measures allow an individual to compare desirable options and choose the one (or several) that is most preferred. As a stand-alone measure, the ipsative approach does not allow an individual to be directly compared to another person’s responses. The measure’s scale scores are only relative to that individual. This attribute of ipsative measures is a major weakness of assessments such as the StrengthsFinder®; however, a major strength of ipsative measures, as normative measures, is they are not nearly as suspectable to social desirability or “faking”.
Normative measures allow an individual to endorse or not endorse a single statement at a time and then the pattern of the individual’s responses is compared to the patterns of normality. The major strength of this normative approach is that it allows an individual to be compared to a normative sample (e.g., job applicants, adult workforce, particular groups, and/or populations); however, a major weakness of normative measures is their susceptibility to social desirability or “faking”. This attribute of normative measures is a major weakness of assessments such as the HPI®, DiSC®, and MBTI®.
TBM incorporates normative measures so that inter-individual difference comparisons can be made, and it also incorporates ipsative measures so that variance due to social desirability can be accounted and used for prediction.