The study examines the effect of inflation, investment, life expectancy and literacy rate on per capita GDP across 20 countries using ordinary least squares regression. Initially, the regression results show inflation, investment and literacy rate have a negative effect, while life expectancy has a positive effect on per capita GDP. Sri Lanka, USA and Japan are identified as potential outliers based on their high residuals. Running the regression after removing these outliers improves the model fit and explanatory power of the variables. Diagnostic tests find no evidence of misspecification or heteroskedasticity, validating the OLS estimates.