R&D DISCLOSURE PATTERNS AND INDUSTRY ANALYSIS: A COMPREHENSIVE STUDY OF THAI LISTED COMPANIES

Abstract

This study investigates patterns of research and development (R&D) disclosure among firms included in the SET 100 Index of the Stock Exchange of Thailand through a content analysis of annual reports (Form 56-1). The sample comprises 76 listed companies observed over the period 2019–2021, yielding 228 firm-year observations. Disclosure quality is assessed using a multidimensional R&D Disclosure Score (RDS) ranging from 0 to 9, encompassing three disclosure domains: research activities, development activities, and integrated R&D reporting. Reliability testing demonstrates strong consistency between evaluators, with Cohen’s κ values of 0.85 for binary coding and 0.81 for sub-score assessments. To examine determinants of disclosure quality, Ordered Logistic Regression is employed while controlling for firm size, leverage, profitability, market-to-book ratio, and board independence. The findings indicate that industry affiliation exerts a significant influence on disclosure practices (Nagelkerke R² = 0.18, p < 0.01). Although the vast majority of firms (92.1%) provide at least some R&D-related information, only 49.1% achieve a comprehensive level of disclosure. Statistically significant variation is observed across industries (χ² = 15.8, p < 0.05), with companies operating in the Industrials and Agro & Food sectors exhibiting substantially higher disclosure levels than those within the Services sector. The results further reveal a progressive enhancement in reporting quality over time, as the proportion of firms providing comprehensive disclosure increased from 46.1% in 2019 to 53.9% in 2021 (p < 0.01). Among the various disclosure categories, research expenditure is reported most frequently (71.9%), followed by development expenditure (65.8%) and combined R&D information (57.0%). This pattern aligns with the expectations of Signalling Theory, which suggests that organisations are more willing to disclose information perceived as less strategically sensitive. Nevertheless, the findings also demonstrate that disclosure behaviour cannot be fully explained by Signalling Theory alone. Differences in governance quality and institutional policy environments appear to contribute materially to reporting practices, indicating that R&D disclosure within the Thai capital market is shaped by broader institutional influences. The validated RDS framework and the baseline evidence established in this study provide a foundation for future investigations linking disclosure practices to capital market consequences and may assist in the development of governance-oriented disclosure frameworks across emerging ASEAN economies.