# Engineering the Future: Evaluation of Virtual Reality Across Project Lifecycle Stages
## 4 Results
### Confirmatory Factor Analysis of Perceived Practiality of VR Across Project Lifecycle Stages  
CFA was conducted to validate the unifactorial structure of the latent variable perceived practicality of VR, based on seven ordinal indicators: Proposal and Investor Recruitment, Specification and Requirement Definition, Concept Formation, Design and Surveys, Development, Testing, Training, and Maintenance. These items captured participants' perceptions of VR's usefulness across different project stages. The analysis used the DWLS estimator with NLMINB optimization. An analysis of item-total statistics using methods appropriate for ordinal data was conducted to evaluate the internal consistency of the eight-item scale designed to measure the perceived practicality of VR across different project lifecycle stages. This examination reveals how each item interrelates with the others and its impact on overall scale reliability, primarily using Ordinal Alpha, which is Cronbach's Alpha based on polychoric correlations, and McDonald's Omega. The overall Ordinal Alpha for the eight-item scale was found to be 0.75, suggesting acceptable internal consistency. To understand each item's contribution, two key metrics were examined: the corrected item-total correlation (representing the correlation of an item with the total score of the remaining items, based on polychoric correlations) and the Ordinal Alpha if the item were deleted. The item Proposal and Investor Recruitment showed an acceptable corrected item-total correlation of 0.37; removing this item would slightly decrease the Ordinal Alpha to 0.73. In contrast, Specification and Requirement Definition exhibited a very low corrected item-total correlation of 0.13. Notably, removing this item would increase the Ordinal Alpha to 0.78, indicating that this item does not align well with the others, and its removal enhances the scale's internal consistency. For Concept Formation, the corrected item-total correlation was 0.38, and removing it would slightly lower the Ordinal Alpha to 0.73. The item Design and Surveys demonstrated a strong corrected item-total correlation of 0.66, and its removal would substantially decrease the Ordinal Alpha to 0.68, highlighting its significant contribution to the scale's reliability. Similarly, Development had a strong corrected item-total correlation of 0.64, and its removal would also notably lower the Ordinal Alpha to 0.68. The item Testing showed a good corrected item-total correlation of 0.55, and removing it would decrease the Ordinal Alpha to 0.70. Training had a corrected item-total correlation of 0.43, and its removal would result in an Ordinal Alpha of 0.72. Lastly, Maintenance exhibited a corrected item-total correlation of 0.41, and if removed, the Ordinal Alpha would be 0.73. Further assessment of reliability, aiming to validate the scale's coherence using a different but related measure, involved calculating McDonald's Omega. This was based on polychoric correlations for the eight items and assumed a unidimensional structure, yielding an Omega Total (\(\omega\)t) of 0.76. This value also indicates acceptable reliability and is consistent with the Ordinal Alpha. The general factor loadings from this omega analysis, derived from a Schmid-Leiman solution, indicated varied contributions from the items to this general factor. Specifically, Design and Surveys (loading = 0.77) and Development (loading = 0.77) showed the highest loadings. These were followed by Testing (loading = 0.72), Maintenance (loading = 0.53), Training (loading = 0.46), Concept Formation (loading = 0.42), and Proposal and Investor Recruitment (loading = 0.38). The item Specification and Requirement Definition had a negligible loading on this general factor, as its loading was below the print threshold of 0.2, and its variance explained by the general factor (h2) was only 0.02, further supporting its misalignment with the other items.