Momentary level:	$y_{ijk}\text{(nostalgia)}={\pi }_{1jk}\text{(activity present dummy code)}+{\pi }_{2jk}\text{(activity absent dummy code)}+{\pi }_{3jk}\text{(time)}+e_{ijk}$
Day level:	$\text{activity present:}{\pi }_{1jk}={\beta }_{10k}+r_{1jk}$
	$\text{activity absent:}{\pi }_{2jk}={\beta }_{20k}+r_{2jk}$
	$\text{time:}{\pi }_{3jk}={\beta }_{30k}+r_{3jk}$
Person-level:	$\text{activity present:}{\text{β}}_{10k}={\text{γ}}_{100}+u_{10k}$
	$\text{activity absent:}{\text{β}}_{20k}={\text{γ}}_{200}+u_{20k}$
	$\text{time:}{\text{β}}_{30k}={\text{γ}}_{300}+u_{30k}$