The Evolution of Rotation Group Bias: Will the Real Unemployment Rate Please Stand Up?
研究发现美国当前人口调查（CPS）中失业率随样本轮换月份系统变化的偏差随时间加剧，1994年调查重新设计后偏差显著增大，调查无回答率上升是重要原因。
We document that rotation group bias—the tendency for the unemployment rate to vary systematically by month in sample—in the Current Population Survey (CPS) has worsened over time. Estimated unemployment rates for earlier rotation groups have grown sharply relative to later rotation groups; both should be nationally representative samples. This bias increased discretely after the 1994 CPS redesign, and rising nonresponse rates are likely a significant contributor. Survey nonresponse increased after the redesign, mirroring the evolution of rotation group bias. Consistent with this explanation, rotation group bias for households that responded in all eight interviews remained stable over time.