In this section, we will detail the application of SLR. According to [3], the SLR is a methodology that consists of identifying, collecting, and analyzing relevant articles within the literature. First, we identified the Goal-Question-Metric approach (GQM) [4]. According to [4], the GQM approach is an intensive method to specify useful metrics by identifying goals and objectives for the process, specifying goals with data or metrics, and finally, using a framework to interpret the data according to the defined goals.
The research questions are an essential part of any SLR [5] since they drive the search methodology. To designate pertinent studies concerning IoT and to sense technology research to support people with autism, we proposed the following research questions:
- RQ1: Which type of action can be currently performed for the affected individuals by autism using IoT?
- RQ2: Which IoT approaches for autism are examined and evaluated in this work?
- RQ3: Which techniques and technologies are combined with IoT?
- RQ4: What are the validation measures for ASD approach?
- RQ5: What types of wearable/non-wearable devices and sensors have been implemented?
In particular, our purpose was to define the current state-of-art of autism support using IoT (RQ1), the proposed approach in the paper (RQ2), techniques and technologies reported in action, the techniques that were implemented with IoT in the approach, and the kind of metrics used for testing and validating the approach, and (RQ3) and (RQ4), respectively. In addition, we examined the types of wearable/non-wearable devices and sensors that are applied (RQ5).
To answer these questions and identify relevant papers for this review, we adopted the SLR guidelines presented in [5]. In the next section, “Search strategy,” we identify the search terms and the source of resources
2.1 Search Strategy
Based on [5], it is important to define a search strategy; accordingly, in this section, we will identify the search terms and the search resources. For the identification of the search terms, a typical method is to divide the subject into separate components, such as population, intervention and outcomes, and context. A list of synonyms, abbreviations, and alternate spellings should then be created. By looking at the subject headings used in journals and databases, more keywords can be found. Sophisticated search words can then be developed using Boolean ANDs and ORs.
Search terms
Five instructions are defined in [5]:
- The identification of population, intervention, and outcome is:
- Population: autism;
- Intervention: IoT;
- Outcome: Kind of action.
For example, the research question can be formulated like this:
- The identification of synonyms:
- Autism (“autism” OR “Autism Spectrum Disorder” OR “ASD” OR “autistic people” OR “Children affected by autism” OR “individuals on the spectrum disorder”);
- IoT (“Internet of Things” OR “IoT” OR “Sensing technology” OR “sensors”);
- The analysis of keywords in each research study
- The formulation of search queries using “OR” and “AND” operators. The operator “AND” is for concatenation. For example :
The formulation of a search query with a limited number of Boolean operators. For example:
Search resources
The main search resources used were Google Scholar, Springer, IEEE, ACM, Science Direct, SCOPUS, PubMed, and Wiley.
In the next section, “Papers selection process,” we specify the steps of retrieving pertinent papers, the search criteria, and the quality assessment to select the relevant research.
The keyword selection procedure
We searched for relevant papers concerning significant IoT applications for supporting autism. Search keywords were identified according to the research questions and all associated topics addressed in this review, and four keywords related to IoT and autism were specified in the search term. The obtained list of keywords was: Autism, IoT, Learning, Supporting Autism, Sensing Technology, and Autism Spectrum Disorder (ASD). However, this list was not exhaustive; indeed, some additional or alternative keywords were changed to reduce the risk of missing important and related publications.
2.2 Papers selection process
In this section, we will identify how the research articles were selected for this review. The process of the selection of related studies is illustrated as follows:
More than 50 articles were retrieved from the initial selection using the selected databases. Meanwhile, some papers (for example, papers that were referenced in a retrieved paper from a database) were searched manually.
In the succeeding stage, we applied inclusion and inclusion factors. We detail this part in the “Search Criteria” paragraph. The result of this selection was 42. The quality of the rest of the papers was evaluated using the criteria specified in the paragraph: “Quality assessment.”
Search Criteria
Following SLR, we applied two types of criteria:
Inclusion Criteria:
- Research not concerned with autism;
- Research not concerned with IoT or sensing technology;
- Research not written in English;
- Research not in peer-reviewed journals or conferences, books, and lecture notes;
- Research written before 2012.
Exclusion Criteria:
- Research published between 2012 and 2022;
- Research that used keywords;
- Research that exploited IoT to support and diagnose autism;
- Full version (not abstract) research.
The result of the “Search Criteria” step gathered 53 research papers.
Quality Assessment
In this phase, we verify the collected papers from the previous step in detail. According to SLR, we conduct this phase with a set of questions. We asked the following questions as they pertained to each research article’s approach:
- Q1: Is the approach presented?
- Q2: Is the proposed solution specified in detail?
- Q3: Is the IoT applied?
- Q4: Are the validation strategies and performance measures explicitly detailed?
- Q5: Has the approach been tested in a real environment?
Each selected paper had a score that corresponded to the quality. According to the scoring procedure specified by SLR, each question was scored as: “YES” = 1, “Partially” = 0.5, “NO” = 0, or Unknown. The score of the paper was the sum of the five questions scored. Then, we categorized the research quality as “High (score ≥ 4),” “Medium (3≤ score < 4),” and “Low (score < 3).” Hence, a paper with the highest quality had five. Only papers having medium or high scores were selected.
Data collection
The final studies that passed all selection steps (Table 1) were examined to reply to the research questions. For this purpose, we propose the classification of papers in the next section. Then, we aim to answer the research questions in the “Results” sections.