Lugtig, Peter. “The Relative Size of Measurement Error and Attrition Error in a Panel Survey. Comparing Them With New Multi-Trait Multi-Method Model.”. Survey Research Methods 11, no. 4 (December 13, 2017): 369-382. Accessed November 15, 2019. https://ojs.ub.uni-konstanz.de/srm/article/view/7170.