2. Study 1
The aim of Study 1 was to examine a new 5-item instrument designed to assess the
Big-Five personality dimensions. We used four tests to evaluate the instrument, each
time comparing the 5-item instrument to the BFI. First, to assess convergent and discriminant
validity, we obtained self-ratings, observer ratings, and peer ratings using
the 5-item instrument and the BFI.
Second, to assess test–retest reliability, a sub-sample of participants took the revised
5-item instrument and the BFI a second time, two weeks after the first test administration.
Test–retest correlations are particularly valuable for single-item
measures because internal-consistency indices of reliability cannot be computed.
Third, to examine patterns of external correlates, we also obtained self-ratings on
several other measures. The construct validity of an instrument can be defined in
terms of a nomological network (Cronbach & Meehl, 1955); that is, the degree to
which a construct shows theoretically predicted patterns of correlations with other
related and unrelated constructs. Our goal here was not to validate the Big-Five constructs
but to evaluate the degree to which a very brief measure of the Big-Five constructs
assesses the same constructs as those assessed by a longer, established
measure. Therefore, the predicted nomological network for the 5-item instrument
was provided by the pattern of correlations shown by the standard BFI to a broad
range of constructs.
Fourth, to evaluate the convergence between self and observer reports, a sub-sample
of participants were rated by observers after a brief getting acquainted exercise.
(These data were also used to examine convergent and discriminant correlations in
observer reports.)