I noticed that there is some variability in how cross-level interactions are estimated in the literature. Here's a basic model, as specified in the MPlus Users' Guide:
%WITHIN% s | y ON x; %BETWEEN% y s ON w xm; y WITH S;
Some people include the "y WITH s;" statement to estimate the residual correlation between the slope and DV, whereas others do not. What is the rationale for including the "y WITH s;" statement? Are there situations where it is sensible to leave that statement out? Thanks!