PSYC 2P25 Chapter Notes - Chapter 1: Standard Score, Standard Deviation, Trait Theory
9 Nov 2012
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There is not usually a meaningful zero level of a psychological trait. In psychology, we are not able to describe ratios between people"s levels of a variable or a person"s absolute amount of a variable. Ways of measuring: ranking people, observation. Scores are converted into standard scores: the first step in calculating a standard score is to take an individual"s score on a given scale, and then subtract the mean score for the person"s that have been measured. Standard scores have two special properties: the average score on a standard-score scale is exactly one. That way after we have calculated the scores, we can meaningfully compare a person"s scores across different variables. After we have calculated the scores, we can easily figure out the extent to which the two variables go together, or correlate. The extent to which it agrees with other measurements of the same variable.
