Effects Description Mean Response Structure* (1.1) No group difference (1.2) Difference between groups constant across 24-hour sequence (1.3) Group-specific mean response functions have different quadratic trends (1.4) Group-specific mean response functions smoothed differently using distinct vectors of coefficients for OSA and Control profiles (1.5) Separate smoothing and distinct smoothing parameters for OSA and Control profiles Same as structure (1.4) but differing variances for smoothing coefficients: and

The term OSAi indicates whether subject belongs to the OSA or Control group (1=OSA, 0=Control); similarly, CTRi indicates group membership for spline-based differences (1=Control, 0=otherwise).

Table 1: Class of semiparametric mixed models to evaluate group-specific differences in twenty-four hour diastolic blood pressure.