Random error, as with most error in research design is not “error” in the sense of being an obvious mistake. Rather, it is variability that occurs in data due simply to natural inconsistency that exists in the world. Random error does not alter the measured values of a variable in a consistent or systematic way, but it does contribute to an imperfect measure of a variable.
Random error contributes variability in all data collection measures, such that according to [Page 1202]classical test theory, the observed value of a variable (x0) is not actually the “true” value of the variable, but instead it is the true value (xt) of the variable plus the value of the error (e). This idea can be written as x0 ...
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