1. Assessing ‘the Big Five’ personality factors McCrae and Costa (1987)
Matt Jarvis
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2. Validation of the five-factor model of personality across instruments and observers
Generalisability of the sample The researchers used a sample of 274 Americans from a single district. The sample size is reasonably large, which makes it more generalisable. There was a good age range, further enhancing generalisability. However, the fact that the sample was entirely American is a problem for generalisability. A good approach to explaining personality should generalise across a range of cultures and having an all-American sample means that this may not be possible. The lexical hypothesis adds to problems of generalisability because the personality terms used were all from the English language. There may be important personality concepts in other cultures that cannot be easily captured using English.
Hodder & Stoughton © 2016

3. Validation of the five-factor model of personality across instruments and observers
Cross-cultural validity of the lexical hypothesis The validity of the procedure depends on the validity of the five personality factors being studied. This in turn depends on the lexical hypothesis. If the lexical hypothesis is dodgy then we can end up with a rigorous study of a nonsense idea. A potential problem with the lexical hypothesis is its cross-cultural validity. There may be important concepts related to personality that are important in other cultures but which cannot be easily captured using English. A replication using the German language (Saucier and Ostendorf, 1999) supported the existence of the five factors but they still may not describe personality in all cultures.
Hodder & Stoughton © 2016

4. Validation of the five-factor model of personality across instruments and observers
Practical applications in personality testing The findings of the study provide strong support for the five-factor model of personality – at least when used to describe Americans. This means that when we are looking for a way to describe personality in real life situations this is probably one of the better systems. The major application of personality theory is personality testing, used in job selection, dating profiles and to satisfy people who are generally curious about themselves. Some studies have supported the predictive validity of the five-factor model. For example Rothman & Coetzer (2003) found that three of the factors; stability, agreeableness and openness were strongly predictive of work performance amongst managers.
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5. Validation of the five-factor model of personality across instruments and observers
Internal and external reliability of the procedure Internal reliability is said to be good when all participants have a very similar experience. External reliability is said to be good when the procedure can be replicated and when similar results are found on doing so. The procedure used by McCrae and Costa is straightforward to run so that all participants have a very similar experience and to replicate. There are published replications by independent researchers (for example Saucier and Ostendorf, 1999), which do indeed show similar findings.
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