> "...why the “official” one is still measured at all."
"The official measure provides a consistent historical view of poverty in the United States, but the SPM may be better suited to helping congressional policymakers and other experts understand how taxes and government programs affect the poor. Also, it may better illustrate how certain medical expenses and work-related expenses such as child care can affect a family's economic well-being."
"One of the most important differences between the two measures, however, is that the SPM is intended to be revised periodically, using improved data sources and measurement techniques as they become available, while the official poverty measure is intended to remain consistent over time."
"The official measure provides a consistent historical view of poverty in the United States, but the SPM may be better suited to helping congressional policymakers and other experts understand how taxes and government programs affect the poor. Also, it may better illustrate how certain medical expenses and work-related expenses such as child care can affect a family's economic well-being."
"One of the most important differences between the two measures, however, is that the SPM is intended to be revised periodically, using improved data sources and measurement techniques as they become available, while the official poverty measure is intended to remain consistent over time."
Both quotes are from "The Supplemental Poverty Measure: Its Core Concepts, Development, and Use" at https://www.congress.gov/crs-product/R45031