Important: the findings below relate to Belbin results produced via our purpose-built system, which analyses and norms test scores to produce a detailed report unique to the individual. Please note: there is no sanctioned self-scoring Belbin test available and use of one is likely to be in breach of our copyright.
What is test reliability?
In psychometric testing, a reliable test is one which will produce consistent results when the same person is tested on different occasions. Whilst Belbin isn’t a psychometric test (Belbin measures behaviour rather than personality), peer-reviewed research demonstrates that Belbin reliability is good across all Team Roles.
The other consideration is the test’s validity -- whether the test measures what it claims to measure. When evaluating a test, reliability is usually measured before validity, because the reliability of a test places an upper limit on its validity. In other words, a test cannot measure what it purports to measure unless it offers stable and consistent measurement.
There are two kinds of reliability: test-retest and internal consistency.
Test-retest reliability measures the extent to which items in an inventory measure the same construct or trait. The most common measure of test-retest reliability is called Cronbach’s alpha.
A score of 0.6 or above is considered acceptable; a score of 0.7 or above is good.
The alpha scores for each Team Role are shown below.
Team Role CF CO IMP ME PL RI SH SP TW
Alpha (a) .77 .75 .80 .77 .84 .71 .77 .67 .72
Table: Belbin reliability scores
Reliability is good or acceptable for all nine roles.
Belbin measures behaviour rather than personality. Whilst personality remains fairly static, we would expect behaviour to change depending on the situation. For example, we might respond to a change in job role by cultivating different working styles. However, it is unlikely that an individual’s Team Roles will reverse entirely.
Each Belbin Team Role is a cluster of behaviours, observed in Dr Belbin’s original research.
Internal consistency is highest where test items are repeated, but this narrows the focus of the test overall. Rather than repeating questions exactly, the Belbin test (the Self-Perception Inventory) looks for clusters of related behaviour. For example, the Co-ordinator cluster refers to an individual who is consultative, conscious of priorities, mature in approach and who seeks out the contributions of others. However, that does not mean to say that everyone who is consultative will necessarily be conscious of priorities.
Beware... some studies of the Belbin Self-Perception Inventory refer to the old, self-scoring version of the inventory which is not used to produce the Belbin Individual Report and is protected by copyright. Find out more about the real Belbin and how we’re building high-performing teams.
For a general introduction to Belbin Team Roles, including preferred, manageable and least preferred roles - Team Roles in a Nutshell
For more in-depth information on Belbin reliability and validity - Belbin Team Roles - A Comprehensive Review of Reliability and Validity
For a peer-reviewed study examining Cronbach’s Alpha in relation to the Belbin SPI - The Belbin Team Role inventory: Reinterpreting reliability estimates