The researchers tested the simple effect of tutoring within each grade level.
研究人员在每个年级水平内检验了辅导的简单效应。
Because the interaction was significant, we examined the simple effects of the treatment at low and high stress levels.
由于交互作用显著,我们进一步考察了在低压力与高压力水平下该处理的简单效应。