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Reliability and Validity

Reliability and Validity. What is Reliability?. A measure is considered reliable when: there is very little error in the measurement Measurement remains constant under specific conditions. Types of Error. Random Systematic. Effect of Unreliable Measures. Meaningless results

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Reliability and Validity

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  1. Reliability and Validity

  2. What is Reliability? • A measure is considered reliable when: • there is very little error in the measurement • Measurement remains constant under specific conditions

  3. Types of Error • Random • Systematic

  4. Effect of Unreliable Measures • Meaningless results • Inappropriate conclusions

  5. Test-Retest Reliability • Equipment reliability • Intertester reliability • Intratester reliability

  6. Interclass Correlation Coefficient • Measure multiple times • Assess consistency of measure • Pearson r • -1.0 - 1.0 • -1.0 = perfect negative linear relationship • 0 = no linear relationship • 1.0 = perfect positive linear relationship

  7. Intraclass Correlation Coefficient • ICC • Sensitive to changes in: • Calibration • Error from one test to next • Multiple tester interaction • Sources of variance • Between subjects • Between occasions • Interaction between subject and test • Error

  8. Outcomes for the ICC • Table 9-1 • Table 9-2 • Table 9-3 • Table 9-4

  9. ICC Calculation • Repeated measures ANOVA • ICC calculated from • BMS • TMS • EMS

  10. Precision • Standard error of the measure • SEM • As reliability increases SEM decreases

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