Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
Using US cross-section data, holiday gift giving is a normal good whose income elasticity of demand is about 0.5. As income rose 1914–2000, aggregate holiday gift expenditure grew as well. Since 2000, however, holiday giving has fallen in real terms as income has continued to rise. While gift giving remains normal in household cross sections, it behaves like an inferior good in the post-2000 national time series.