Parental consent procedures: Impact on response rates and nonresponse bias.
Doumas, D. M., Esp, S., & Hausheer, R. (2015). Parental consent procedures: Impact on response rates and nonresponse bias. Journal of Substance Abuse and Alcoholism, 3(2), pp. 1031-1 – 1031-4.
Does the requirement of getting active consent from parents in school-based research result in a biased sample? An empirical study.
Jelsma, J., Burgess, T., & Henley, L. (2012). Does the requirement of getting active consent from parents in school-based research result in a biased sample? An empirical study. Journal of Empirical Research on Human Research Ethics, 7(5), pp. 56-62.