Before revision: Types Sampling bias Sampling bias is systematic error due to a non-random sample of a population,Medical Dictionary - 'Sampling Bias' Retrieved on September 23, 2009 causing some members of the population to be less likely to be included than others, resulting in a biased sample, defined as a statistical sample of a population (or non-human factors) in which all participants are not equally balanced or objectively represented.TheFreeDictionary → biased sample.
After revision: of biasTypes Sampling bias Sampling bias is systematic error due to a non-random sample of a population,Medical Dictionary - 'Sampling Bias' Retrieved on September 23, 2009 causing some members of the population to be less likely to be included than others, resulting in a biased sample, defined as a statistical sample of a population (or non-human factors) in which all participants are not equally balanced or objectively represented.TheFreeDictionary → biased sample.