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Measurement

Measurement. 17.871 Spring 2003. Topics in Measurement. From abstraction to measure Sources of error What to do about error Practical ways to improve measurement. The Mapping. Theory. Y. X. y. x. Observation. e y. e x. Mapping from the Abstract to the Measurement.

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Measurement

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  1. Measurement 17.871 Spring 2003

  2. Topics in Measurement • From abstraction to measure • Sources of error • What to do about error • Practical ways to improve measurement

  3. The Mapping Theory Y X y x Observation ey ex

  4. Mapping from the Abstract to the Measurement • Some abstract things we try to measure • Alienation • Moral decay • Democracy • Party identification • Fear of defeat • Terrorism • Ideology

  5. Sources of Error in Measurement(Mosteller) • Conceptual or design error • Bad breaks in random sampling • Survey question wording • Non-random out-selection • Transcription errors • Calculation & mechanization errors

  6. What to Do About Error • Practice safe data • Know where your data come from • Watch for anomalies • Use multiple measurement techniques • Collect as much data as possible and disaggregate

  7. Practical things to do about measurement • Distinction between a measure and an indicator • Measure: straightforward quantification of a variable of interest • Indicator: quantification of a variable that is believed (or known) to be highly correlated with the “real” variable of interest

  8. Examples of Measures • Income in $$ • Age in years • Votes • Number of wars (hmmmmmm…..) • Campaign contributions • Measurement issues tend to focus on the quality of the data-gathering method, especially sampling

  9. Examples of Indicators • Public opinion • Party identification • Trust in government • Ideology • Economics • Gross domestic (national) product • Characterizations of political systems • Freedom • Transparency • Democracy

  10. How do we generate indicators? • Trust others and hope for the best • GDP, etc. • Presidential approval • Use a single measure and hope for the best (or convince ourselves it’s OK) • 7-point ideology scale • 7-point party identification scale • Codings of “wars” or “rally events” • Bulletin of the Atomic Scientist “nuclear clock” • Use multiple measures creatively

  11. Multiple-measure indicators • “Trust in government” battery • How much of the time do you think you can trust the government in Washington to do what is right? • Would you say the government is pretty much run by a few big interests looking out for themselves or that it is run for the benefit of all the people? • Do you think that people in the government waste a lot of money we pay in taxes, waste some of it, or don’t waste very much of it? • Do you think that quite a few of the people running the government crooked, not very many are, or do you think hardly any of them are crooked? • External political efficacy battery • Sometimes politics and government seem so complicated that a person like me can’t really understand what’s going on • People like me don’t have any say about what the government does • Public officials don’t care much what people like me think.

  12. Trust and Efficacy over Time

  13. Other Multiple-Variable Indicators • Americans for Democratic Action Support Scores • Freedom House freedom assessment • MIT Teaching Quality • Transparency International’s “Corruption Perceptions Index” • DNominate Scores

  14. ScalingOr, How to Create Multiple Indicators More Generally

  15. Imagine an unobserved factor that gives rise to observable factors • Democracy • Healthiness • Racism • Conservatism • Religiosity Measure 1 e1 b1 Measure 2 e2 Unobserved factor b2 . . . bn Measure n e3 Fairness of elections e1 b1 Meaningfulness of elections e2 Polyarchy b2 b3 Freedom of expression e3 b4 Unbiased reporting of official pronouncements e4

  16. Two-factor (pure) polyarchy example Fairness of elections Freedom of expression A B C D E F G H I J Polyarchy Polyarchy

  17. What We Observe in the Pure Case Fairness of elections Freedom of expression

  18. Two-factor (impure) polyarchy example Fairness of elections Freedom of expression A B C D E F G H I J Polyarchy Polyarchy

  19. What We Observe in the Impure Case Fairness of elections Polyarchy

  20. Congo, Lebanon Hungary Bhutan USSR, Libya, Iran, China Jamaica, Greece Egypt, Sri Lanka, Mexico Peru, India, Israel Argentina, U.S., Finland Source: http://www.nd.edu/~mcoppedg/crd/polydat.htm

  21. Simple way to create multiple-indicator scale with just 1 factor

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