Research Psych

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  1. Measure of Variability
    • Measures of variability describe the extent
    • to which scores in a distribution differ from each other
  2. The Range
    • The range indicates the distance
    • between the two most extreme scores in a distribution
  3. Variance and Standard Deviation
    • two measures of variability that indicate
    • how much the scores are spread out around the mean

    • •We use the mean as our reference point since
    • it is at the center of the distribution
  4. SampleVariance
    / Sample Standard Deviation
    • sample variance is the average of the squared deviations of
    • scores around the sample mean

    ´╗┐´╗┐Formula:
  5. Computational Formula:
  6. Population Variance
    Formula
  7. Population Standard Deviation
    Formula
  8. Estimated Population Variance
    • By dividing the numerator of the sample
    • variance by N - 1, we have an unbiased
    • estimator of the population variance

    Formula:
  9. Estimated Population Variance
    Computational formula
  10. Estimated Population Standard Deviation
    • By dividing the numerator of the sample
    • standard deviation by N - 1, we have an unbiased
    • estimator of the population standard deviation.

    Formula
  11. Unbiased Estimators
    • 1.
    • 2.
    • Quantity N-1 is called the degrees of freedom
  12. Proportion of Variance Accounted For
    • proportion of variance accounted for is the proportion of
    • error in our predictions when we use the overall mean to predict scores that is eliminated when we use the relationship with another variable to predict scores
Author:
Anonymous
ID:
8349
Card Set:
Research Psych
Updated:
2010-02-27 19:49:06
Tags:
Statistics
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Description:
Psych Exam
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