@article{Groves2008,
author = {Groves, R.M. and Peytcheva, E. },
title= {The impact of nonresponse rates on nonresponse bias},
year = {2008},
doi = {10.1093/poq/nfn011},
journal = {Public Opinion Quarterly },
volume = {72},
number = {2},
pages = {167−189},
}