The mrsprep command restructures survival data and calculates weighted mean expected mortality rates and time-dependent weights so that a marginal relative survival can be directly estimated. After running mrsprep estimation commands that fit (conditional) relative survival models (e.
stpp calculates the Pohar-Perme non-parametric estimate of marginal relative survival, which under assumptions can be interpreted as marginal net survival. The estimate is a step function and changes at each event time.