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EPE/EDP 557

EPE/EDP 557. Correlation Definition Correlation vs Causation Calculations & Tests Pearson r (interval or ratio data) Spearman rho (ordinal data) Chi Square Overview Important Concepts & Calculations Requirements. EPE/EDP 557. Correlation Definition Correlation vs Causation

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EPE/EDP 557

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  1. EPE/EDP 557 • Correlation • Definition • Correlation vs Causation • Calculations & Tests • Pearson r (interval or ratio data) • Spearman rho (ordinal data) • Chi Square • Overview • Important Concepts & Calculations • Requirements

  2. EPE/EDP 557 • Correlation • Definition • Correlation vs Causation • Calculations & Tests • Pearson r (interval or ratio data) • Spearman rho (ordinal data)

  3. EPE/EDP 557 • Correlation • From: • Co- “with, together” • -relation “association” • Changes in one event/measurement are associated with changes in another event/measurement • Correlation Coefficient: a numerical measure of association (-1 to +1) • Positive, Negative, & Zero Correlations

  4. EPE/EDP 557 • Correlation vs Causation

  5. EPE/EDP 557 • Pearson r • Requirements for use • Randomly selected sample • Measured traits are relatively normally distributed • Interval or ratio data • Variation in both distributions roughly similar • Linear association

  6. EPE/EDP 557 • Pearson r (correlation coefficient): • Coefficient of Determination: • The proportion of variability in Y that can be explained by variability in X

  7. EPE/EDP 557 • Spearman rho • Requirements for use • Randomly selected sample • Both distribution in ordinal form • Linear association

  8. EPE/EDP 557 • Spearman rho: • where d = the absolute value of (Rank1 – Rank2)

  9. EPE/EDP 557 • Chi Square: • Overview • Important Concepts & Calculations • Requirements

  10. EPE/EDP 557 • Chi Square: • Requirements: • Randomly selected samples • Nominal data • Independent cell entries • No expected frequency under 5

  11. EPE/EDP 557 • Chi Square: • where: • Frequency due to chance: • Observed frequency: • Degrees of freedom: • For 1 X k Chi Square: df = k-1 • For r X k Chi Square: df = (r-1)(k-1)

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