why use the lavaan function why use lavaan why use a lavaan function why use sem for exploratory analysis why use lavaan why use lavaan in exploratory analysis why use lavaan why use sem in excel or r what is lavaan used for in statistics? why use lavaan in exploratory regression analysis why use lavaan what is lavaan used for why use sim instead of lavaan which function uses multiplication of variables in a regression analysis? why use a sem package for regression analysis what package to use for a regression analysis why do i need lavaan why use lavaan lavaan vs sem why use lavaan