@article{bates.etal2015, author = {Douglas Bates and Martin Mächler and Ben Bolker and Steve Walker}, date = {2015}, doi = {10.18637/jss.v067.i01}, journaltitle = {Journal of Statistical Software}, number = {1}, pages = {1--48}, title = {Fitting Linear Mixed-Effect Models Using {lme4}}, volume = {67}, }