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Quick Review

Quick Review. Central tendency: Mean, Median, Mode Shape: Normal, Skewed, Modality Variability: Standard Deviation, Variance. Quick Review. Evaluating scores. Raw score of X: -Measure of absolute standing Difficult to interpret Z-SCORE - Measure of relative standing. Z-Transformation.

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Quick Review

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  1. Quick Review • Central tendency: Mean, Median, Mode • Shape: Normal, Skewed, Modality • Variability: Standard Deviation, Variance

  2. Quick Review

  3. Evaluating scores • Raw score of X: • -Measure of absolute standing • Difficult to interpret • Z-SCORE • - Measure of relative standing

  4. Z-Transformation • Transforming all raw scores in a distribution does not change the shape of a distribution, it does change the mean and the standard deviation

  5. Z Transformation • Z transformation provides a common metric to compare scores on different variables • Given X , find Z • Given Z , find X

  6. Find Z

  7. Find X

  8. -THEORETICAL PROBABILITY DISTRIBUTIONS (Z, F, T) -Used for testing hypothesis -Provide a way of determining probability of an obtained sample result (experimental outcome) -Usually, the probably that experimental result occurred by chance given null distribution

  9. A THEORETICAL PROBABILITY DISTRIBUTION The standard normal curve: - Bell-Shaped, symmetrical, asymptotic - Mean, Median and Mode all equal - Mean = 0; SD (δ) = 1; Variance (δ2) = 1

  10. Area under curve  probability Z is continuous so one can only compute probability for a range of values THE NORMAL CURVE

  11. BASIC RULES TO REMEMBER: THE (STANDARD) NORMAL CURVE

  12. BASIC RULES TO REMEMBER: 50% above Z=0, 50% below Z = 0 34% between Z=0 & Z= 1 / between Z=0 & Z = -1 68% between Z = -1 and Z = +1 96% between Z = -2 and Z = +2 99% between Z = -3 and Z = +3 THE (STANDARD) NORMAL CURVE

  13. TWO-TAILED CRITICAL VALUES 5% + and -1.96 1% + and – 2.58 THE (STANDARD) NORMAL CURVE

  14. ONE-TAILED CRITICAL VALUES 5% + OR - 1.645 1% + OR – 2.33 THE NORMAL CURVE

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