Internal Consistency
Cronbach alpha coefficients have ranged between .75 and .90, usually being closer to the upper estimates
(e.g., Jonsson & Allwood, 2003 ;Kleitman & Stankov, 2007 ;Stankov & Crawford, 1996a, b ;Stankov et al., 2008 ;
Stankov & Lee, 2008 ). These tend to be higher than estimates for the corresponding accuracy scores and slightly
lower than for speed measures. These results have been replicated across different cognitive domains and despite
variations in the number of test items employed.
Reliability
Test/C0Retest
Test/C0retest reliability coefficients between confidence judgments acquired from parallel tests completed at
two and four weeks ranged from .85 to .87 ( Jonsson & Allwood, 2003 ).Kleitman and Costa (2014) reported a
test/C0retest coefficient for confidence scores used in formative assessments across the semester to be .94.
Validity
Convergent/Concurrent
Correlations between accuracy and confidence scores from the same test tend to range between .40 and .60
(see Stankov, 1999; 2013 , for a review). In other words, on average, smarter people tend to be more confident
about their performance. These findings support Koriat et al. (2000) suggestion that both variables depend, at
least in part, on the online feedback from the cognitive process of answering a question.
Self-concept about competencies of one’s own memory and reasoning abilities ( Kleitman, 2008; Kleitman &
Stankov, 2007; Stankov & Lee, 2008 ) also predicts confidence levels aft er controlling for accuracy of perfor-
mance. Recent studies with both adolescents and 9 to 11- year-old children clearly show that confidence has
variance in common with metacognitive self-beliefs an d, in particular, with academic beliefs, self-efficacy
and domain-relevant anxiety ( Kleitman & Gibson, 2011; Kleitman & Costa , 2014; Stankov et al., 2012 ;
Morony et al., 2013 ). There is some recent evidence that these me asures of self-beliefs, together with mea-
sures of confidence, tend to define a separate Self-beliefs factor ( Morony et al., 2013; Stankov et al., 2012 ). To
our knowledge, however, there have been no investigat ions into the relationships between online metacogni-
tive Confidence and self-belief Confidence measured by the self-report measures described earlier in this
chapter.
Divergent/Discriminant
Empirical studies have shown only small or non-existe nt correlations between the Confidence trait and all
but the Openness to Experience ( r5.30) personality dimension ( Buratti et al., 2013; Dahl, Allwood,
Rennemark, & Hagberg 2010; Kleitman, 2008; Pallier e t al., 2002; Schaefer, Williams, Goodie, & Campbell
2004 ). Openness to Experience, however, also tends to corr elate about .30 with cognitive performance. Given
the robust relationship between Confidence and cogni tive performance, it is not surprising that people who
score high on Openness tend to have somewhat higher l evels of confidence. Thus, the Confidence factor is
not a part of the personality taxonomy but lies on the ‘no- man’s-land’ between personality and cognitive abil-
ities ( Stankov et al., 1999 ).
Construct/Factor Analytic
When measured across different items, cognitive tests, and knowledge domains, a Confidence factor tends to
emerge /C0using exploratory and confirmatory factor analytic techniques /C0reflecting the stability of those confi-
dence judgments (see Stankov, Lee et al., 2012 ;Stankov, Pallier et al., 2012 ). Some studies also included atypical
tasks/C0e.g., the Sureness scale of Kleitman and Stankov (2007) described above. That is, despite this diversity of
tasks, whether it is to solve a task, predict future events, or simply state one’s views, a Confidence factor tends to
appear signifying the habitual nature and consistency of peoples’ confidence. This factor has been equally pro-
nounced among children aged 9 /C012 years ( Kleitman & Gibson, 2011; Kleitman et al. 2010; Kleitman et al., 2013 ),
adolescents ( Stankov, Lee et al., 2012; Morony et al., 2013 ) and adults (e.g., Kleitman, 2008 ;Stankov & Crawford,
1996a,b ;Pallier et al., 2002 ;Stankov, 2000 ;Stankov & Lee, 2008 ).
Criterion/Predictive
School Achievement: Higher confidence, measured with confidence ratings, has been a strong predictor of
academic achievement. For example, in a sample of primary-school children (9 to 12-year-olds; N5183), higher178 7. MEASURES OF THE TRAIT OF CONFIDENCE
II. EMOTIONAL DISPOSITIONS