Research productivity is a crucial indicator of medical school performance. Adequate investment in research is crucial to support research activities. This study evaluated the efficacy of the research investment strategies employed by a large medical school in Thailand, a developing nation. We analyzed changes in direct research investments (internal grants, equipment, and human resources) and research output of the school over 5 years (2016–2020). Its annual research investment grew from 171.1 to 219.4 million Baht (28% increase). On average, 36.4%, 46.3%, and 17.8% of the budgets were allocated to internal grants, equipment, and personnel, respectively. Concurrently, external research grants increased from 276.6 to 376.2 million Baht (36% higher), and yearly publications rose from 873 to 1148 (31.5% more). Qualitative improvements were noted: publications in quartile 1 journals climbed from 361 to 571, and the mean impact factor advanced from 3.08 to 3.58. This growth was notably robust compared to the sluggish growth during the preceding five years. Correlational analyses explored the relationship between annual publication output and each investment category: grants, equipment, and labor. The strongest correlation and highest slope were observed for human resource investment. This correlation does not necessarily imply a causal relationship or a superior benefit-cost ratio of investing in staffing. However, a questionnaire survey revealed that 47% of researchers at the medical school ranked human resource investment as providing the greatest benefit to their work. In comparison, 45% and 3% of the researchers ranked grants and hardware, respectively, as having the most benefit. These findings suggest that prioritizing investment in personnel is essential. However, maintaining investments in internal grants and equipment remains essential. A balanced distribution of funds and effective management should yield optimal results.

Keywords: Medical investment; Medical output; Research investment; Research output