# Virtual Reality or Videoconferencing for Online Learning? Evidence from Comparative Meta-Analyses
## 3 Method
### Inclusion and Exclusion Criteria  
Articles meeting the following criteria were included in the study. The inclusion criteria were as follows:  
1. The publication year was limited to the period between 2003 and 2023. The reason for choosing 2003 as the starting year for the literature search is that it marked the launch of Second Life, an innovative three-dimensional virtual world that has had a profound impact on the evolution of VR.
2. Only English-language articles published in peer-reviewed academic journals were eligible for inclusion.
3. Studies that used either a randomized controlled trial (RCT) or quasi-experimental design were considered.
4. The subjects of the studies were students in K-12 or higher education.
5. The studies compared online learning facilitated by VR with those conducted under non-VR conditions. We also made an identical provision for articles about VC platforms.
6. The dependent variables measured were related to learning effects. The exclusion criteria were as follows:  
1. Both the experimental and control groups used VR or VC platforms;
2. The research employed augmented reality, mixed reality, or other technological approaches besides VR;
3. The studies did not provide sufficient data, such as sample size and mean values, to calculate the effect size.  
Figure 2 displays an overview of the literature search procedure following the PRISMA protocol [76]. This study identified 507 duplicate articles through a synergistic approach that combined automated recognition tools with meticulous manual screening. Preliminary scanning of the titles and abstracts led to the exclusion of 1645 articles that failed to meet the predefined inclusion criteria. The excluded articles encompassed a variety of categories: some focused on vocational education as their research domain; others relied on methodologies such as surveys, interviews, or case studies; and a subset merely measured the attitudes of the participants. At this stage, 166 articles were obtained for furtherevaluation. During the second round of screening, 137 articles were excluded after reading the full text according to the criteria outlined above. A total of 29 articles meeting all the criteria were thus included in the meta-analyses, of which 15 were related to VR and the remaining 14 were related to VC platforms.  
Given the relatively small number of eligible studies, it was necessary to extract multiple effect sizes from some articles to ensure adequate data coverage. For articles with multiple measures of different types of learning outcomes, or with more than one experimental or control condition, the following principles were used to calculate the effect size: (a) if multiple measurements were reported for the same type of learning outcome (e.g., several post-test scores for knowledge), the average effect size was computed to represent that outcome; (b) if different types of learning outcomes were measured (e.g., using tests for changes in knowledge and scales for changes in attitude), one effect value was extracted for each dependent variable; (c) when there were multiple experimental or control groups (e.g., comparison between VR, VC platforms, and face-to-face instruction in the study), one effect value was extracted for each comparison between VR and non-VR treatment, and between VC and non-VC treatment. As a result, the total number of independent studies included was greater than the number of articles; the number of VR-related studies was 37 and the number of VC platform-related studies was 35.