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Measuring Instruments

Last modified by Sofia Kostakonti on 2022/04/04 12:04

For the evaluation of a prototype, there are several frameworks that can be followed, starting with DECIDE (Kurniawan, 2004). Decide stands for:

  • Determine the goals
  • Explore the questions
  • Choose evaluation approach and methods
  • Identify practical issues
  • Decide about ethical issues
  • Evaluate, analyze, interpret, present data

First, we would have to determine the high-level goals for the study and the motivation behind them, since they can influence how we approach it. Then, we choose the evaluation approach, the methods that will be used, whether these are based on quantitative or qualitative data, and the process of data collecting, analysis, and presentation. At the same time, any practical issues, such as participants, budget, or schedule, are identified and a pilot study is performed if needed. It is important to adhere to any ethical procedures that are in place, to ensure the participant knows their rights and is protected. Finally, the evaluation of the data takes place, where it is determined whether the results are in any way unreliable, invalid, biased, related to the environment and whether they generalize well.

Another framework often used is IMPACT (Benyon et al., 2005):

  • Intention
  • Measures and metrics
  • People
  • Activities
  • Context
  • Technologies

These are the several elements that need to be considered when trying to establish evaluation objectives. First, we should present the objectives and the claims of the study. Furthermore, the specific measures and metrics that will be used need to be determined, followed by the participants and the activities they will perform based on a specific use case. We should also define the context, social, ethical, physical, or environmental, and finally, we must decide on the technologies we will use, both regarding hardware and software.

Regarding the evaluation methods, there are two types: formative and summative evaluation. The formative evaluation is based on open-ended questions that have to do with specific processes of the interaction, whereas the summative evaluation focuses on the overall effect and summarizes whether the objective has been reached. For measuring these evaluations, both qualitative and quantitative data can be examined. The goal of the qualitative data is to explore and discover patterns and themes and that of the quantitative data is to describe, explain and predict based on the outcomes. A combination of the two is often optimal.

Another factor that needs to be considered during an evaluation study is the experiment design. There are two types: the within-subjects design and the between-subject design. The former calls for performing all the test conditions on all participants and getting repeated measures. This design needs fewer subjects and reduces the variance, however, there is the possibility of carry-over effects from one interaction to the next and the setup can be more challenging since it requires more time. The latter is performed on different groups of participants, each undergoing only one test condition. It is much simpler to execute but there might be greater variance due to inter-subject differences in characteristics.

When executing an experiment, it is also interesting to examine the interaction from multiple lenses, in order to identify issues and opportunities that are not immediately obvious. That can mean from the perspective of a different stakeholder that is not the main user, other groups that might not directly interact with the system or even a more technical or legal perspective.

For our study, the process we followed mostly resembles the IMPACT framework since we focused on each of these elements separately and tried to combine them to build our evaluation study. We first defined our research questions and then decided how we could best evaluate them. We decided on a within-subject design and a combination of quantitative and qualitative data. The element of the participants for our study was quite predetermined since we didn't have the access to people with actual dementia, therefore we would use students, peers, and friends to test our hypotheses. By examining our use cases, we thought that the most interesting one we wanted to test was the meal discourse, and consequently, we defined the rest of the aspects regarding the prototype, the experimentation process, and the environment. Our experiment in detail can be found in the Evaluation -> Test  section.

  1. Kurniawan, S. (2004). Interaction design: Beyond human-computer interaction by Preece, Sharp and Rogers (2001), ISBN 0471492787.
  2. Benyon, D., Turner, P., & Turner, S. (2005). Designing interactive systems: People, activities, contexts, technologies. Pearson Education.