Relaibility

Internal Consistency

Internal consistency reliabilities (CronbachÕs Alpha) were computed on samples 1 and 5 from the standardisation exercise. The coefficients are computed over both the combined males and females for each relevant sample. The table below provides these coefficients separately for each sample and for the entire normative sample.

15FQ™ Internal Consistencies & Item Total Correlations (ITC's)

Scale	Items		N=5456	N=5577
		Alpha	ITC	Alpha	ITC	Alpha	ITC
Outgoing	10	0.70	0.18	0.72	0.20	0.74	0.22
Calm-stable	11	0.67	0.16	0.63	0.14	0.65	0.15
Assertive	10	0.64	0.15	0.66	0.16	0.66	0.16
Enthusiastic	12	0.73	0.19	0.76	0.20	0.76	0.21
Conscientious	11	0.72	0.19	0.65	0.15	0.67	0.16
Socially Bold	10	0.79	0.27	0.80	0.29	0.79	0.28
Intuitive	13	0.69	0.15	0.74	0.18	0.73	0.18
Suspicious	14	0.74	0.17	0.73	0.17	0.73	0.16
Conceptual	12	0.72	0.18	0.69	0.17	0.70	0.16
Restrained	12	0.65	0.14	0.64	0.14	0.65	0.14
Self-Doubting	11	0.77	0.24	0.74	0.23	0.76	0.24
Radical	10	0.73	0.21	0.71	0.21	0.72	0.21
Self-sufficient	10	0.66	0.16	0.72	0.18	0.70	0.19
Disciplined	11	0.80	0.28	0.74	0.25	0.76	0.23
Tense-Driven	10	0.66	0.17	0.68	0.18	0.67	0.17
Distortion	13	0.75	0.19	0.69	0.14	0.72	0.16

In addition, the mean 'corrected' item-total correlations for each scale are also reported for each of these samples. These parameters index the average association between the constituent items within a scale and the scale score itself. Each individual item-scale score coefficient is corrected for the inflation of the coefficient due to the item's inclusion in the scale score. The above table provides the number of items which make up each scale.

This table shows that all the 15FQ™ dimensions have internal consistency reliability coefficients above .64 indicating that the test dimensions have an acceptable level of reliability. It can be seen that the reliabilities hold up quite well across the two sub groups reported above. The reliability of these scales compares very favourably with the reliability coefficients reported in the user manuals for both the OPQ and 16PF. As a number of authors have noted many of the 16PF factors are very unreliable with few of the alpha coefficients being greater than .7 and many in fact being lower than .5. Similarly the majority of the scales in the OPQ Concept and Factor models have alpha coefficients of less than .6 and a number have alpha's of less than .5.

The following table provides a comparison of the reliabilities of the 15FQ™ scales with the comparable scales of the 16PF-A, 16PF-C and 16PF-5. The 16PF-A sample consisted of 1785 management applicants, the form C sample of 131 undergraduates, while the 15FQ™ sample is the total standardisation sample for the 15FQ™. As can be seen, only one 16PF-A scale (Tense) is more reliable than its 15FQ™ counterpart. The 16PF-A reliabilities range between 0.18 and 0.78, this compares with a range of 0.60 to 0.87 for 16PF-5 and 0.65 to 0.79 for the 15FQ™.

Comparison of 16PF-A, 16PF-C, 16PF-5 & 15FQ™

	16PF Labels	16PF-A	16PF-C	16PF-5	15FQ™	15FQ™ Labels
A	Warm	.46	.38	.69	.74	Outgoing
C	Calm-stable	.41	.58	.73	.65	Calm-stable
E	Assertive	.56	.28	.68	.66	Assertive
F	Happy-go-lucky	.68	.32	.74	.76	Enthusiastic
G	Conscientious	.61	.45	.70	.67	Conscientious
H	Venturesome	.78	.67	.87	.79	Socially Bold
I	Tender-minded	.58	.46	.76	.73	Intuitive
L	Sceptical	.47	.35	.60	.73	Suspicious
M	Imaginative	.18	.38	.71	.70	Conceptual
N	Calculating	.20	.27	.72	.65	Restrained
O	Apprehensive	.53	.70	.77	.76	Self-doubting
Q1	Experimenting	.34	.26	.65	.72	Radical
Q2	Self-sufficient	.36	.58	.75	.70	Self-sufficient
Q3	Controlled	.53	.58	.74	.76	Disciplined
Q4	Tense	.73	.41	.73	.67	Tense-driven
Social Desirability		.38	.63	.72	Distortion

Stability

The next table displays temporal consistency data for the 15FQ™. Both short-term (2 weeks), obtained from a sample of 80 undergraduates, and long-term (4 months) from a sample of 83 volunteers. This table demonstrates that the 15FQ™, has a high degree of temporal consistency over the periods reported. These test-retest coefficients compare highly favourably with those reported for similar personality instruments. The short-term SEMs are all well below 1 sten.

Short & Long-term Test-Retest Coefficients for the 15FQ™ (N=80, N=83)

15FQ™ Scales	Short-term Test-retest	Long-Term Test-retest	Short-term SEM	Long-term SEM
Outgoing	0.85	0.80	0.77	0.89
Calm-stable	0.83	0.71	0.82	1.08
Assertive	0.84	0.78	0.80	0.94
Enthusiastic	0.85	0.88	0.77	0.69
Conscientious	0.84	0.68	0.80	1.13
Socially Bold	0.88	0.85	0.69	0.77
Intuitive	0.83	0.80	0.82	0.89
Suspicious	0.85	0.76	0.77	0.98
Conceptual	0.86	0.70	0.75	1.10
Restrained	0.84	0.87	0.80	0.72
Self-doubting	0.82	0.71	0.85	1.08
Radical	0.87	0.78	0.72	0.94
Self-sufficient	0.85	0.79	0.77	0.92
Disciplined	0.90	0.79	0.63	0.92
Tense-driven	0.80	0.78	0.89	0.94
Distortion	0.82	0.77	0.85	0.96