## 2 Literature Review
### Economic Sectors' Effect on Income  
This research primarily focuses on the impact of sectoral composition and industrial development, as outlined earlier. While the influence of various factors on income has been widely studied, the effect of productivity across different economic sectors on income is not as well-explored. Previous studies have identified infrastructure development within the construction sector as a robust predictor of economic growth across various regions ([PERSON], 2011; [PERSON] et al., 2012). Additionally, sectoral shifts, particularly from low-productivity activities like agriculture to higher productivity activities, often result in increased GDP per capita ([PERSON] and [PERSON], 2012). However, a study by [PERSON] et al. (2010) found that the level of employment in the manufacturing sector, traditionally linked with robust economic growth, did not significantly impact median household income growth. The transition from manufacturing to service sectors has also led to broader structural changes in the economy, affecting job types and income distribution ([PERSON] et al., 2003; [PERSON] et al., 2007; [PERSON] and [PERSON], 2000). The influence of sectors such as wholesale and retail trade, finance, insurance, real estate, health, and construction on regional income dynamics is complex and multifaceted. [PERSON] et al. (2010) also noted that employment levels in sectors often seen as indicators of economic maturity, like wholesale, retail, finance, insurance, real estate, and health, do not consistently show significant effects on employment or median household income growth, highlighting their ambiguous role in economic development. This issue is particularly relevant in the case of Thailand, a developing nation that distinguished itself in the 1990s with a notably higher per capita income compared to other middle-income countries. However, Thailand's income growth has stagnated since the Asian economic crisis in 1997, struggling to achieve a significant breakthrough. This stagnation is evident in the comparison chart provided in the Appendix A (Figure 11), illustrating Thailand's income trajectory in relation to other similar economies. To the best of our knowledge, there is a notable lack of comprehensive studies directly linking the diversity of economic sectors to average household income in Thailand. Most existing research on regional economic development in the country emphasises the role of specific policies, such as the One Tambon One Product (OTOP) initiative, and their impact on fostering entrepreneurship and growth ([PERSON] et al., 2023). The OTOP initiative has been pivotal in harnessing local skills and resources for the development and commercialisation of products, primarily in sectors like food and beverage, and local craft manufacturing ([PERSON] and [PERSON], 2016). However, the predominance of OTOP products in these limited sectors may inadvertently overlook other economic sectors with significant growth potential. Moreover, a significant study modelled Gross Provincial Product (GPP) as an outcome variable, highlighting labour in the formal system and the level of investment as key factors influencing GPP ([PERSON], 2023). This finding indicates the potential impact of public and private investment in specific economic sectors on the long-term welfare of citizens. Yet, the effects of various economic sectors on household income remain largely unexplored. This gap highlights the necessity to examine the influence of sectoral productivity on income dynamics. Such an investigation could provide valuable insights into Thailand's economic challenges and identify viable avenues for sustainable growth. This research addresses a research gap stemming from the limited understanding of how specific sectors or the characteristics of sectoral composition affect household income.