How the SDI is unique in the world of assessments


he heart and soul of Core Strengths is the SDI. The SDI is a valid and reliable psychological assessment, used by millions, since 1971. The following illuminates how the SDI compares to some other popular assessments in the market.

The idea that there are different types of people has been part of human culture about as long as there has been human culture. But the methods of determining and categorizing types of people are incredibly diverse, ranging from birth circumstances to physical characteristics to psychological constructs.

We can say someone was born under the astrological sign Leo, or was born in the Year of the Rooster, or is a first-born. In certain circles, this is enough to convey that person’s personality. Stereotypes based on physical characteristics such as height, weight, or gender (e.g. short men have a Napoleon Complex, or blonde women lack intelligence) are not scientifically valid, yet they persist.

Non-scientific types, which are, at best, misleading, and, at worst, dehumanizing or used to justify cruelty, are usually based on traits that do not require sophisticated measurement. Psychological types are different. They describe processes or characteristics that are not directly observable.

Behind any valid, reliable, and practical personality assessment, there is a theory of psychology and individual differences. Every theorist, in order to establish a typology of these differences, makes assumptions about which differences are most important and should serve as the basis for the typology. This means that every theorist, and therefore every assessment, looks at the same people through a slightly different lens.

Many facilitators are asked (by their employers, stakeholders, or learners in the classroom) to compare various assessments that are commonly used in workplace training and development programs. Questions such as “If I’m a high D on DISC, will I be a Red on SDI?” or “Aren’t all Greens on SDI also Introverts on MBTI?” should be expected. The simple, surface-level, conceptual correlations are appealing, but often incomplete. The most effective way to compare assessments is to begin by comparing the theories on which they are based – including a look into the theorists’ mindsets and intentions. The following brief comparison of theories highlights only a few key points.

Porter and SDI Theory

The Strength Deployment Inventory is based on Relationship Awareness Theory, by Elias Porter. Porter, a peer of Carl Rogers, was interested in how people develop, how they get in touch with their authentic selves and become productive adults. He wanted to create a tool to help people – something they could use to understand themselves more completely and accurately.

Porter came to the belief that people’s strivings in relationships, their motives, reasons for doing things, and values, would serve as the most useful basis for personality types. This belief was built on the foundation laid by psychoanalysts such as Erich Fromm and Sigmund Freud. Porter, however, made two significant departures from these previous theorists: 1) he focused on productive strengths and motives, not problems or pathologies, and 2) he assumed that the person was the expert on themselves, whereas traditional psychoanalysis relies on the therapist’s observations.

Marston and DISC Theory

While there are many versions of DISC assessments available, and the letters may indicate different words in various versions, most acknowledge William Marston as at least a key contributor or originator of the concept. Marston, like Porter, was interested in authenticity and the effects of the environment on people’s actions. Marston invented the systolic blood pressure test, which is a key part of the polygraph (lie-detector). He also created the comic-hero Wonder Woman, with her lasso of truth.

Marston observed that people’s actions changed in different environments, and these changes in response to situations are the basis for the DISC types. For example, Wonder Woman’s Dominance (activity in an antagonistic environment) secures the bad guy’s Compliance (passivity in an antagonistic environment). However, these actions can only be considered in a specific context, they are not necessarily enduring characteristics of the people.

Jung and MBTI Theory

Many assessments are based on Carl Jung’s theory of psychological types, including MBTI and Insights. Jung was originally an adherent to Freud’s personality theories, but he disagreed about the importance of relationships in personality formation and did not believe that motives were the most useful way to classify types of people. Jung believed that archetypes were part of the inherited and collective unconscious, a mystical concept that has been criticized by many scientists.

However, Jung’s observations about Introversion and Extraversion have stood the tests of time and science. Jung believed that internal mental processes, or functions and attitudes, should serve as the basis for types. The attitude of Introversion or Extraversion, when combined with one of four dominant functions (Sensing, Intuition, Thinking, or Feeling) formed the basis of Jung’s typology, which has since been expanded on by others.

How Total SDI Complements Other Assessments

A person with a Red MVS may be Extroverted and Domineering. However, another person with a Red MVS may be Introverted and Influential. Every assessment assumes a point of view; to the extent that these views differ, they can generally be complementary. It is easy to imagine some similarities, as well as some differences, between the two people with a Red MVS.

The MVS explains a lot about a person’s motives and reasons for doing things, but it does not explain everything; no assessment does. Every assessment needs to take a limited view in order to produce a valid and reliable result. Just as taking more than one measurement at a physical examination produces a more comprehensive picture of the physical condition, more than one personality assessment can be useful in understanding people. There is no single test to determine everything about the human body or the human mind.

The SDI explains motives under two conditions 1) when things are going well, and 2) when facing conflict. It is based on a theory of interpersonal relationships. The SDI easily complements other assessments, such as DISC and MBTI, that do not represent motives and are focused on individual behaviors or internal processes.

Advantages of TotalSDI over Other Assessments

From a practical perspective, many organizations choose to standardize one assessment, or allocate only enough time for one assessment in a training and development program. In these circumstances, market forces lead to competition between assessments and raise questions such as “Which assessment is best?”

The answer to that question depends on the objective of the user. If the objectives include improving the quality of relationships, the SDI has a clear advantage because it is based on a theory of relationships. From Relationship Awareness Theory, practical advantages emerge, such as the ease of charting team results or multiple relationships on a single SDI Triangle. Team views tend to be extraordinarily cumbersome when generated by other assessments that are based on internal phenomena such as one’s perception of the environment or data-collecting process.

DISC, at least at its roots, is not a personality theory in the traditional sense because it does not describe enduring characteristics of people. The theory is that people change their behavior in response to their perceptions of situations. This is what many DISC assessments measure. The risk with using DISC is that people treat each other as though the DISC profile represents an enduring personality, when, in reality, the DISC result should change when the person is in a new situation.

MBTI and other assessments derived from Jung’s work suffer from an assumption in the underlying theory that does not hold up. Namely, that traits, such as Introversion and Extraversion are opposites or dichotomies. In fact, many people who complete MBTI believe that they are neither Introverted nor Extraverted, but some of each. More scientifically valid and reliable measures treat Introversion and Extraversion as a single scale and find that the majority of people fall in the middle (or mean) of the scale and lack a clear preference for Introversion or Extraversion.

The SDI describes personality as a dynamic system under two conditions. It shows the degrees of people’s motives and how they blend or interact. It is not limited to providing only names or letters for types. The SDI Triangle converts the numbers to a visual representation, which allows a result to be close to or on a border. This enables a subtler, richer, and more accurate presentation of the results. The SDI is simple; it has exceptionally high face-validity (almost everyone agrees with their results), and it is memorable. Being memorable is a prerequisite to being useful; if people forget their results (as is unfortunately the case with many other assessments) they have no chance of putting those results to work for them.

The SDI can be used to enhance things that teams and organizations have done, or are currently doing. But sometimes, there is limited space or time and the SDI is a very practical and adaptable tool to promote as a standard within all types of interpersonal skills training.