Application of Industry‐Specific Sample Strata in PPI Variance Estimation

Teresa E. Hesley

Abstract

The Producer Price Index (PPI) uses industry specific strata in their sample design. The PPI samples each of its industries independently. Establishments are typically selected at the six-digit NAICS level, though some industries are sampled as high as the three-digit level. Since PPI designs their samples on an industry by industry basis, each sample may have strata based on attributes of that industry. In the initial development of the variance estimation method, which makes use of the bootstrap method, replicates were selected over the whole of the industry. The purpose of this paper is to describe a PPI variance estimation method which takes into account the industry specific stratification..