Whether workers' characteristics influence their unemployment duration is inconclusive in the existing literature in Taiwan. This study traces those persons unemployed in May and resampled in June in the data of the Manpower Utilization Survey conducted by the Directorate-General, Budget, Accounting, and Statistics (DGBAS). It is found that conclusions of insignificance and opposite signs of workers' characteristics in the existing literature are likely due to data used and omission of reservation wage. It is shown that with reservation wage, all explanatory variables of workers' characteristics are significant. On the contrary, without reservation wage, all workers' characteristics are insignificant. It implies a severe omitted variable problem. Results of estimates under unobserved heteroscedasticity are consistent with the model without unobserved heteroscedasticity.