Psychology 2080A/B Chapter Notes - Chapter 4: Joseph L. Fleiss, Confidence Interval, Interpersonal Communication
9 Apr 2013
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The word error does not imply that a mistake has been made, error implies that there will always be some inaccuracy in our measurements. Tests that are relatively free of measurement error are deemed to be reliable. In 1733 abraham de moivre introduced the basic notion of sampling error. Karl person developed the product moment of correlation. Cronbach and his colleagues made a major advance by developing methods for evaluating many sources of error in behavioural research. Classical test score theory assumes that each person has a true score that would be obtained if there were no errors in measurement. The score observed for each person almost always differs from the persons true ability or characteristic. A major assumption in classical test theory is that errors of measurement are random. Basic sampling theory tells us that the distribution of random errors is bell- shaped. The dispersions around the true score tell us how much error there is in the measure.
