The TAM allowed us to measure usefulness and ease of use in a subjective manner; the Think Aloud method allowed us to analyze these measures objectively.
Regarding the evaluation of measures for SPC, Tarhan and Demirors [36, 37] defined measure usefulness to SPC as a requirement for choosing a process to SPC.
Second, the preliminary item pool was rated regarding face validity (the extent to which an item appears to measure usefulness) and wording, including independent external raters (N = 18).
The primary outcome measure (usefulness rate) was defined as the percentage of excellent or good outcomes according to the criteria noted above.
We measured usefulness with three items [ 59] that asked whether the health recommendation system (1) was not useful/useful, (2) was not useful/useful to improve nutrition, and (3) would not/would influence purchases.
The four-page self-assessment questionnaire included the USE, three global items to measure usefulness, questions on demographic characteristics, previous knowledge about the respective illness, and the CIRF (adaptation of the scale is described below).
In a chronic illness such as those causing intestinal inflammation, where quantifiable absolute survival (as in cancer) is not relevant, issues such as accuracy, preference and cost become paramount in measuring usefulness.
We replicated the ANOVAs with two alternative measures for usefulness, mean usefulness rating and number of usefulness ratings above 5, to check that our choice of usefulness score did not unduly impact our analysis.
This approach represents knowledge by means of the concept of utility [7] known from economics, which measures the usefulness from the researchers' and the service providers' perspective.
Here, the support and confidence (user parameter/input) indicate the measures of usefulness and certainty of the rule, respectively.
