Intro to Psychological Testing (part II)

Clinical Judgment Do clinicians have special powers of intuition? Can clinicians predict behavior better than other people? Does experience improve clinicians’ judgments?

Factors That Limit Clinical Judgment Lack of feedback on outcomes Inability to use feedback (hindsight bias) Confirmation bias Illusory correlations and missing cells Weighting information inappropriately Overconfidence

Some Principles of Test Interpretation Extreme scores tell you more than normal range scores Do not over-interpret differences between scales Test interpretations are only hypotheses, not facts Look for patterns; don’t rely on single indicators Don’t assume the test is wrong if it doesn’t match your intuition

Descriptive Statistics Measures of Central Tendency Mode Mean Median Measures of Variability Standard deviation

Normal Curve

Score Transformations _ z = X – X SD New score = z*NewSD + NewMean T = 10z + 50 IQ = 15z + 100

Correlation Looks at the relationship between two things Scatterplot Correlation coefficient

Restriction of Range