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S519: Evaluation of Information Systems

S519: Evaluation of Information Systems. Social Statistics Inferential Statistics Chapter 16: reliability and validity. This week. What are reliability and validity. Scales of measurement. What is measurement: The assignment of values to outcomes following a set of rules

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S519: Evaluation of Information Systems

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  1. S519: Evaluation of Information Systems Social Statistics Inferential Statistics Chapter 16: reliability and validity

  2. This week • What are reliability and validity

  3. Scales of measurement • What is measurement: • The assignment of values to outcomes following a set of rules • The scales of measurement have four types: • Nominal, ordinal, interval and ratio

  4. Nominal level of measurement • An outcome can fit into one and only one class or category • E.g. gender, political affiliation • The least precise level of measurement • Categories should be mutually exclusive

  5. Ordinal level of measurement • Things are ordered • E.g., a rank of candidates for a job

  6. Interval level of measurement • Equal intervals but zero does not indicate absence • temperature in Celsius • temperature in Fahrenheit

  7. Ratio level of measurement • The presence of an absolute zero on the scale • In biological sciences, zero molecular movement, zero light • Height, weight, etc. temperature in Kelvin

  8. In sum • Any outcome can be assigned to one of the four scales of measurement • Scales of measurement have an order, from the least precise being nominal, to the most precise being ratio • The “higher up” the scale of measurement, the more precise the data being collected, and the more detailed and informative the data are

  9. In sum

  10. Reliability • Whether a test, or whatever you use as a measurement tool, measures something consistently • Reliability = “consistency”

  11. Some ways for reliability • Test-retest reliability • Want to examine whether a test is reliable over time • Compute the Pearson correlation coefficient on scores from a test at Time 1 and Time 2

  12. Validity • The property of an assessment tool that indicates that the tool does what it says it does • Validity = “on targetness” • Content validity • Validate through domain expert • Criterion validity • Validate your criteria with existing tests or criteria • Literature support

  13. Unreliable and Invalid Shooting

  14. Reliable but Invalid Shooting

  15. Reliable and Valid Shooting

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