ABSTRACT
The use of animals raises scienti¿ c and ethical challenges (Workman et al., 2010). Therefore, an animal experiment should be designed with due consideration to ethics on a solid scienti¿ c platform. Animal experiment should have high precision, but should not waste resources or animals (Festing, 1997). It is important to select an appropriate study design to provide scienti¿ c evaluation of the research ¿ ndings without bias (Lim and Hoffmann, 2007). Replication, randomization and blinding are the key components of the design of the animal experiment. But, these are less often used in animal research (Kilkenny et al., 2009). Hess (2011) reviewed statistical design given in 100 articles on animal experiments published in Cancer Research in 2010. In 14 of the 100 articles, the number of animals used per group was not reported. In none of the 100 articles was the method employed to determine the number of animals used per group reported. Among the 74 articles in which randomization seemed feasible, only 21 reported that they had randomly allocated animals to various groups. None of these articles described how the randomization was carried out.
