For all SPA surveys (including the Tanzania SPA 2014/15), the health facilities are selected by a stratified equal probability systematic sampling, stratification is achieved by crossing region and facility type. The health facility weight is calculated based on the selection probability, and then adjusted for non-response at the sampling stratum level. The provider weight is calculated based on the facility weight multiplied by the inverse of the selection probability of providers; the providers are selected with equal probability by provider type within each of the sampling stratum, and then adjusted for provider non-response. The client weights (ANC visit weight, Family Planning visit weight and Sick child visit weight) are calculated in the same way as for the provider weight, based on the facility weight multiplied by the inverse of the selection probability of clients; the clients are selected with equal probability by client type within each of the sampling stratum, and then adjusted for client non-response. All the sampling weights presented in the data files are normalized weights which are relative weights and are valid for estimating means, proportions, ratios and rates, but not valid for estimating population totals and not valid for pooled data.