A large body of research has supported the reliability and validity of the Personal Behaviour Inventory and the DISC FACTORS.

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

The research findings on test-retest reliability show that the scores on the Personal Behaviour Inventory DISC System 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 Personal Behaviour Inventory is a reliable instrument that consistently measures the same thing.

Construct and concurrent validity studies have compared the Personal Behaviour Inventory with other Four Factor instruments

such as the Discus Personality Profiler, Personal Profile Analysis and TTI ‘s Style. Significant correlations have been found across all four  DISC FACTORS. This indicates that the Personal Behaviour Inventory validly assesses constructs measured by other Four Factor assessment instruments.

Research on content validity has shown that the  DISC FACTORS can differentiate good performances from poor performances. This ability to differentiate has been shown in studies as diverse as sales performance, production operators and team leaders in a number of industries. The Personal Behaviour Inventory can successfully distinguish varying levels of performance.

Criterion or predictive validity studies have looked at the ability of various  DISC FACTORS to predict outcomes. Outcome measures as diverse as sales performance, retention rates and job performance have been predicted with a high degree of accuracy on the basis of DISC scores. This ability to predict makes the Personal Behaviour Inventory a very valuable tool in selection and management, providing it is used alongside good interviewing techniques, and good aptitude tests

Strong Construct Validity is shown when the instrument consistently exhibits content validity, concurrent validity and predictive validity. The research shows the Personal Behaviour Inventory to be a construct valid instrument.

A recent study provides an excellent example of validity of the  DISC FACTORS of the Personal Behaviour Inventory. Top sales people (N=136) were compared with a sample of other professional workers (N= 450)on the DISC Profile. The two groups were found to differ significantly on all  DISC FACTORS. Each of the dimensions of the DISC Profile contributed to the ability to distinguish top sales people from other workers. This study showed that the Personal Behaviour Inventory can identify specific characteristics that are predictive of success.

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

Reliability Estimates

Using 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 =  .93

·             Influence     r = .79

·             Steadiness  r = .84

·             Compliance r = .82

These reliability coefficients indicate that there is an unusually high degree of internal consistency in response to the Personal Behaviour Inventory Instrument as a whole and to each of the related dimensions. A significant measure 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 for our DISC Profiling System 

+/-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