DISC Validity Overview

There have been numerous, formal studies that have been completed with DISC products that show scientific validity in all applicable areas of assessment. What is presented here for your information is a summary of those areas.

There is a logical expectation that a measurement tool actually is assessing what it is suppose to be measuring. The test should consistently find inverse relationships among certain items, for example. Another test for validity involves the outside assessment by qualified professionals regarding the instruments being studied. There are also all kinds of internal statistical tools to use when comparing the results of a testing instrument in order to determine its validity. In all cases the validity of the DISC model has been proved to be at the highest and most consistent levels of any similar tool available today. There have been numerous, formal studies that have been completed with DISC products that show scientific validity in all applicable areas of assessment. What is presented here for your information is a summary of those areas.

There is a logical expectation that a measurement tool actually is assessing what it is suppose to be measuring. The test should consistently find inverse relationships among certain items, for example. Another test for validity involves the outside assessment by qualified professionals regarding the instruments being studied. There are also all kinds of internal statistical tools to use when comparing the results of a testing instrument in order to determine its validity. In all cases the validity of the DISC model has been proved to be at the highest and most consistent levels of any similar tool available today. Validity for the Style Analysis and DISCus Software has been investigated in terms of:

• Face Validity - the test "looks valid" for the people who take it and to untrained colleagues. Current face validity is 91%
• Construction Validity - considers the relationship of the DISC model with related assessments of behavioral style.
• Predictive Validity - refers to the extent in which it could be said a person is likely to become dissatisfied with their work, to become sick, etc.

Reliable Studies

Reliability StudiesUsing the Spearman-Brown “split-halves reliability coefficient,” reliability estimates were obtained. This coefficient indicates the degree of internal consistency of response to the instrument as a whole. The coefficients for each dimension are as follows:

Dominance r =. 92
Influence r =. 89
Steadiness r =. 91
Compliance r =. 90

It is evident from these reliability coefficients that there is an unusually high degree of internal consistency in response to the Style Analysis Instrument as a whole and to each of the related dimensions. Strength of the correlation is indicated by the size of the coefficient. The coefficient can vary from +1.00 through 0 to –1.00. A coefficient near 0 tells us that there is no relationship between the variables. The closer a coefficient is to + or – 1.00, the stronger the relationship.

Correlation Examples+/-1.0 = Perfect correlation (extremely rare)
+/-.80 - .99 = Unusually high correlation
+/-.70 - .79 = Very high correlation
+/-.60 - .69 = High correlation
+/-.30 - .59 = Moderately high correlation
+/-.20 - .29 = Very low correlation
+/-.00 - .19 = No correlation

The study duplicates, in part, a study by Dr. Russell J. Watson, Wheaton College, "Statistical Comparison Between the TTI Style Analysis and the Performax Personal Profile System," 1989.

Reliability of the Style Analysis

A large body of research has supported the reliability and validity of the Style Analysis and the DISC dimensions. This research has provided evidence of high test-retest reliability (the stability of test scores over time); strong Construct Validity (the relationship of the Style Analysis to other tests measuring similar constructs); robust content validity (how well the DISC dimensions measure what they are supposed to measure); significant criterion or predictive validity (the ability of the DISC dimensions to predict performance on another activity); and powerful construct validity (the extent to which the DISC dimensions measure a specific trait).

The research findings on test-retest reliability show that the scores on the Style Analysis exhibit very little change over time. Six-month test-retest correlations average in the .90 range where a correlation of 1.0 is a perfect relationship (absolutely no change) and .0 is no relationship (random change). The Style Analysis is a reliable instrument that consistently measures the same thing.

Construct and concurrent validity studies have compared the Style Analysis with other Four Factor instruments such as the Activity Vector Analysis, Personal Profile Analysis and Clever Self. Significant correlations have been found across all four DISC dimensions. This indicates that the Style Analysis validly assesses constructs measured by other Four Factor assessment instruments.

Research on content validity has shown that the DISC dimensions can differentiate good performances from poor performances. This ability to differentiate has been shown in studies of sales performance and managerial ability in a number of industries. The Style Analysis can successfully distinguish varying levels of performance.

Criterion or predictive validity studies have looked at the ability of various DISC dimensions to predict outcomes. Outcome measures as diverse as sales performance, turnover rates and job injuries have been predicted with a high degree of accuracy on the basis of DISC scores. This ability to predict makes the Style Analysis a very valuable tool in selection and management. 
Strong Construct Validity is shown when the instrument consistently exhibits content validity, concurrent validity and predictive validity. The research shows the Style Analysis to be a construct valid instrument.

A recent study provides an excellent example of validity of the DISC dimensions of the Style Analysis. Top sales people (N=166) were compared with a large sample of other professional workers (N=3448) on the DISC. The two groups were found to differ significantly on all DISC dimensions in both Natural and Adapted style. Each of the dimensions of the DISC contributed to the ability to distinguish top sales people from other workers. In addition, both Natural and Adapted style scores added to the ability to predict job performance. This study showed that the Style Analysis can identify specific characteristics that are predictive of success.

A review of the extensive research that has been conducted on the Style Analysis conclusively shows that the Style Analysis Instrument is a reliable and valid assessment device with a wide range of applications.