KMAN Publication Inc. (KMANPUB) International Journal of Innovation Management and Organizational Behavior (IJIMOB) 3041-8992 6 Serial Number 25 2026 03 30 Threshold Effects of Gross Fixed Capital Formation in the Relationship Between Healthcare Infrastructure and Life Expectancy Index in Iran Threshold Effects of Gross Fixed Capital Formation in the Relationship Between Healthcare Infrastructure and Life Expectancy Index in Iran 1 10 10.61838/kman.ijimob.5072 EN Journal Article 2025 11 05 <table> <tbody> <tr> <td> <p><strong>Objective:</strong> The present study aimed to investigate the threshold effects of gross fixed capital formation on the relationship between healthcare infrastructure and the life expectancy index in Iran.</p> <p><strong>Methods and Materials: </strong>This applied and descriptive–analytical study employed an ex post facto design using annual time-series data for Iran covering the period 1986–2023. The empirical analysis was conducted using EViews software. To examine nonlinear dynamics and potential regime-switching behavior, a first-order Logistic Smooth Transition Regression (LSTR1) model was estimated, with gross fixed capital formation serving as the transition variable. Prior to model estimation, Phillips–Perron unit root tests were applied to assess stationarity, and the Johansen–Juselius cointegration approach was used to test for long-run equilibrium relationships among the variables. The model incorporated healthcare infrastructure indicators, including hospital beds, physicians, nurses and midwives, public and private health sector investment, labor force participation, population growth, and literacy rate. Diagnostic tests were performed to assess autocorrelation, heteroskedasticity, parameter stability, and remaining nonlinearity.</p> <p><strong>Findings: </strong>The results indicate that all variables are integrated of order one and cointegrated in the long run. The linearity test rejects the null hypothesis of linearity, confirming the appropriateness of the LSTR1 specification. Gross fixed capital formation exhibits a statistically significant threshold value of −0.211, dividing the model into two distinct regimes. In the nonlinear (high-capital) regime, the coefficients of gross fixed capital formation, hospital beds, physicians, nurses and midwives, and both public and private health sector investment are positive and statistically significant, with greater magnitudes compared to the low-capital regime. Diagnostic tests confirm the absence of autocorrelation and heteroskedasticity, and parameter constancy tests support regime-dependent coefficient variation. The adjusted R² of 0.88 indicates strong explanatory power.</p> <p><strong>Conclusion: </strong>The findings demonstrate that the effectiveness of healthcare infrastructure in improving life expectancy in Iran is conditional upon the level of gross fixed capital formation. When capital accumulation surpasses a critical threshold, the impact of healthcare infrastructure intensifies significantly, highlighting the importance of sustained macroeconomic investment in enhancing health outcomes.</p> </td> </tr> </tbody> </table> https://journals.kmanpub.com/index.php/ijimob/article/download/5072/9151