Between 2014 and 2023, the dimensions of the allocation matrices for ECERT (certificates), EPROCERT (certifications and licenses), and EWHOCERT[1-4] (type of certification) were incorrectly specified, which means the distributions for imputed data may not align with expectations given respondent characteristics. The impact of these errors on unweighted in-universe data varies by year. The error in EPROCERT also has downstream effects for EWHOCERT[1-4] because the latter’s universe is based on EPROCERT values.

These issues were identified and fixed during 2024 SIPP processing. Data users should be aware of these issues when using ECERT, EPROCERT, and EWHOCERT[1-4], particularly if comparing past estimates with 2024 data.