I
M
A
G
E
B
Y
A
N
G
E
L
L
O
D
E
C
O
risks of patient harm, and are they
proportionate?) and economics (Is
the intervention cost-effective?). The
question regarding health outcomes
is commonly based on the assumption
that the intervention will be used as
intended; in the world of medications,
this is discussed as compliance,
adherence, or conformance, but for
clinical trials, compliance is assumed
(and is a requirement of participants
in the trial). Questions of engagement,
ease of use, or how people fit the
intervention into their lives are rarely
reported. The limitations of clinical
trials for digital interventions are
being recognized [ 4] and variants
that address some of the limitations
are being developed [ 5], but the focus
remains on quantitative (summative)
evaluation of interventions.
Whereas health research tends
to focus on outcome measures, HCI
research tends to focus on user
needs, design rationale, and process
measures. Except where measures
of success relate to time to complete
tasks or error rates, they are often
qualitative, based on user reports
or observations of user experiences
when using technology. Thus, the
focus is commonly on qualitative
(formative) evaluations and on the
ways in which technology is used in
practice by different people, including
workarounds and other unexpected

Figure 1. Proximal and distal evaluation measures, and their disciplines (simplified).
Stable
(software
“works”)

Software engineering Classic HCI Health services Health interventions UX Field studies

Usable
and
useful

Clinically
effective
Scalable
in practice
Engaging
and positive
user
experience
Fits user
context and
care sytem;
used as
intended