Sample Size. The sample size won't and can't be predefined. The most important problem that a predefined sample size is used to avoid - bias in deciding when to stop enrollment -is unlikely to be a problem when the decision to stop enrollment will be based on factors (in this case, the recruitment of hospitalists) that are unlikely to hinge on the accrued results. Another problem that a fixed sample size is intended to avoid is imprecision of the effect size identified. For this study, the precision of this estimate will be limited by the numbers of children who are admitted at the 4 services over the 2-3 year study period. This is likely to be the largest feasible sample size that can be studied, as >8,000 admits are expected in 3 yrs.