A double jackknifing procedure is proposed to include a third source of the estimation error, the error due to common-item sampling. Three different versions of the double jackknifing were implemented and compared. The data used in this study were item responses from Grade 4 students who took the NAEP 2004 and 2008 math long-term trend (LTT) assessments. These student samples used in this study are representative samples of Grade 4 student population in 2004 and in 2008 across the US. The results showed that these three double jackknifing approaches resulted in similar standard error estimates that were slightly higher than the estimates from the traditional approach, regardless of whether an item sampling scheme was used or items were dropped at random.