@article{Udry2003,
author = {Udry, J.R. and Chantala, K.},
title= {Missing school dropouts in surveys does not bias risk estimates},
year = {2003},
doi = {10.1016/S0049-089X(02)00060-1},
journal = {Social Science Research},
volume = {32},
number = {2},
pages = {294--311},
}