1. Bate ST, Clark RA (2014) The design and statistical analysis of animal experiments. Cambridge University Press, New York
2. Mayya SS, Monteiro AD, Ganapathy S (2017) Types of biological variables. J Thorac Dis 9(6):1730–1733
3. Blank BE (2016) Elementary statistics. First president university press. http://math.wustl.edu/~brian/stats/2200-03.pdf
4. Banos JH (2018) Confounding variables. In: Kreutzer J, DeLuca J, Caplan B (eds) Encyclopedia of clinical neuropsychology. Springer, Cham
5. National Academy of Sciences (US), National Academy of Engineering (US) and Institute of Medicine (US) Committee on Ensuring the Utility and Integrity of Research Data in a Digital Age. Ensuring the Integrity, Accessibility, and Stewardship of Research Data in the Digital Age. Washington (DC): National Academies Press (US) (2009) Ensuring the Integrity of Research Data. Available from: https://www.ncbi.nlm.nih.gov/books/NBK215260/6