  Internet Users' Information Privacy Concerns (IUIPC-10) is one of the most
endorsed privacy concern scales. It is widely used in the evaluation of human
factors of PETs and the investigation of the privacy paradox. Even though its
predecessor Concern For Information Privacy (CFIP) has been evaluated
independently and the instrument itself seen some scrutiny, we are still
missing a dedicated confirmation of IUIPC-10, itself. We aim at closing this
gap by systematically analyzing IUIPC's construct validity and reliability. We
obtained three mutually independent samples with a total of $N = 1031$
participants. We conducted a confirmatory factor analysis (CFA) on our main
sample. Having found weaknesses, we established further factor analyses to
assert the dimensionality of IUIPC-10. We proposed a respecified instrument
IUIPC-8 with improved psychometric properties. Finally, we validated our
findings on a validation sample. While we could confirm the overall
three-dimensionality of IUIPC-10, we found that IUIPC-10 consistently failed
construct validity and reliability evaluations, calling into question the
unidimensionality of its sub-scales Awareness and Control. Our respecified
scale IUIPC-8 offers a statistically significantly better model and outperforms
IUIPC-10's construct validity and reliability. The disconfirming evidence on
the construct validity raises doubts how well IUIPC-10 measures the latent
variable information privacy concern. The sub-par reliability could yield
spurious and erratic results as well as attenuate relations with other latent
variables, such as behavior. Thereby, the instrument could confound studies of
human factors of PETs or the privacy paradox, in general.
