@article{Haviland2011,
author = {Haviland, A.B. and Jones, B.L. and Nagin, D.S.},
title= {Group-based trajectory modeling extended to account for nonrandom participant attrition},
year = {2011},
doi = {10.1177/0049124111400041},
journal = {Sociological Methods and Research},
volume = {40},
number = {2},
pages = {367--90},
}