## 4 Results: The Usage of CARIMO
### Methods for Usage Data Analysis
#### Definition of CARIMO User Groups  
User groups for CARIMO were calculated for the test group in total, as well as on a country basis. According to previous usage measurement for AAL technologies [20], the framework used four user groups for assessing the intensity of using a system. 1. _frequent_ users: participants who used a CARIMO feature more often than a regular user. 2. _regular_ users: participants who used a CARIMO feature on a regular basis. 3. _infrequent_ users: participants who used a CARIMO feature less often than a regular user. 4. _non_-users: participants who did not use a CARIMO feature at all. Particularly, the characteristics \"frequent,\" \"regular,\" and \"infrequent\" needed thresholds to assign users to these groups. For the thresholds below, we applied an expert-knowledge-driven approach. Definition of Usage Groups for Body-Related Features of CARIMO  
Body-related features of CARIMO comprised two functions \"fitness exercises\" (training program personalized by sport scientists based on assessments of physical abilities by care workers; see Section 2) and \"activities\" (manually entered into the system by the users or automatically recorded by the activity tracker). We specified thresholds that informed about the frequency of use based on the recommendations for health-enhancing physical activity [62]. In general, for healthy adults aged 65 and above, it is recommended that they perform physical activities of at least 150 min at a moderate intensity or 75 min of vigorous intensity per week [62]. Moderate-intensity corresponds to tasks requiring effort of three to six \"metabolic equivalents\" (METs), e.g., cycling for pleasure or transport (\(\leq\)10 mph), and vigorous intensity corresponds to more than six METs, e.g., cycling fast (\(>\)10 mph) [63]. Table 2 shows the user group definition for the body-related features (fitness exercises, activities, and total). Based on the WHO recommendations and considering the health conditions of our target group, we defined a regular user as a user who does \"fitness exercises\" between 4 and 7 times a month (60 and 105 min) and performs between 9 and 24 \"activities\" a month (225 and 600 min). One run of \"fitness exercises\" was estimated with 15 min and one activity with 25 min. Consequently, a frequent user was defined per the above guidelines and an infrequent user was below the values of a regular user. Definition of Usage Groups for Mind-Related Features of CARIMO  
Mind-related features of the CARIMO app covered \"newspapers\" and \"internet and games,\" where \"newspapers\" was a single feature and \"internet and games\" consisted of two subfeatures. The categories were defined specifically for this study using the expertise of end-user experts, i.e., home care providers. They assumed that people interested in \"newspapers\" (regular users) will use this feature at least 10 times a month. They also stated that highly interested people (frequent users) will use this feature at least 20 times a month. Accordingly, an infrequent user was defined as being below these values (Table 3--Newspapers). For many CARIMO users, it was the first time in their lives that they had internet access. About two thirds of the users did not use the internet before [64]. Thus, the end user experts expected that a regular user would use the internet between 7 and 15 times a month (Table 3--Internet). Participants \begin{table}
\begin{tabular}{c|c c c} \hline \hline
\begin{tabular}{c} Fitness exercises = non AND activities \\ **(Per Month)** \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Usage groups for body-related features. \begin{table}
\begin{tabular}{c|c c c c c} \hline \hline  
who used the internet at least 16 times were defined as frequent users. Usage between 1 and 9 times was classified as infrequent. With respect to \"games,\" a regular user was defined as a user who used games between 8 and 14 times a month. Here too, frequent users were defined above and an infrequent below these values (Table 3--Games).