Crude and adjusted URTI incidence rate ratio (IRR) estimates by level of physical activity and studied covariates, fitted in a hurdle regression model.

Crude and adjusted URTI incidence rate ratio (IRR) estimates by level of physical activity and studied covariates, fitted in a hurdle regression model.通过障碍回归模型（hurdle regression model）拟合得到的、按体力活动水平与纳入研究协变量分层的上呼吸道感染（Upper Respiratory Tract Infection, URTI）粗发病密度比（incidence rate ratio, IRR）与校正后发病密度比的估计值。