chapter g income and expenditures family individual series general note the development of reasonably reliable nationwide estimates distribution for families individuals was dependent on availability comprehensive basic source material from federal tax returns representative sample field surveys incomes annual tabulations return data originated during world war i but until when mini mum requirement filing substantially lowered these provided information only a small fraction upper population samplefield that were designed to cover all occupation groups in nation not introduced 1930 s reflecting lack adequate early estimators had piece together various sets statistics available selected or local areas combine figures with derived by applying yield rates estimated size class distributions wealth among charles b spahr who constructed 1896 willford king