Momentary level:	$y_{ijk}(\text{well-being})={\pi }_{0jk}+{\pi }_{1jk}\text{(nostalgia)}+{\pi }_{2jk}(\text{time})+e_{ijk}$
Day level:	$\text{intercept:}{\text{π}}_{0jk}={\text{β}}_{00k}+r_{0jk}$
	$\text{nostalgia:}{\text{π}}_{1jk}={\text{β}}_{10k}+n_{jk}$
	$\text{time:}{\text{π}}_{2jk}={\text{β}}_{20k}+r_{2jk}$
Person-level:	$\text{intercept:}{\text{β}}_{00\text{k}}={\text{γ}}_{000}+u_{00k}$
	$\text{nostalgia:}{\text{β}}_{10\text{k}}={\text{γ}}_{100}+u_{10k}$
	$\text{time:}{\text{β}}_{20\text{k}}={\text{γ}}_{200}+u_{20k}$