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Measurement and Variables May 14 , 2008

Measurement and Variables May 14 , 2008. Ivan Katchanovski , Ph.D. POL 242Y-Y. Outline. How to design a research project Research questions and research hypotheses Units of analysis Concepts of political science Variables Levels of measurement Nominal Ordinal Interval/ratio

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Measurement and Variables May 14 , 2008

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  1. Measurement and VariablesMay 14 , 2008 Ivan Katchanovski, Ph.D. POL 242Y-Y

  2. Outline • How to design a research project • Research questions and research hypotheses • Units of analysis • Concepts of political science • Variables • Levels of measurement • Nominal • Ordinal • Interval/ratio • Measurement Reliability and Validity

  3. How to Design a Research Project • Define the purpose of your project • Specify exact meanings for the concepts you want to study • Specify a research question or a research hypothesis • Choose a research method • Decide how to measure the results • Decide whom or what to study • Collect empirical data • Process the data • Analyze the data • Report your findings

  4. Research Questions and Research Hypotheses • Research question: a testable question about empirical reality that follows from a more general proposition (a theory) • Is the level of economic development related to democracy • Do women and men vote for different political parties • Research Hypothesis: testable expectation about empirical reality that follows from a more general proposition (a theory) • The level of economic development has a positive effect on democracy • Men are significantly more likely than women to vote for the Conservative Party of Canada • Research is designed to answer research questions or test hypotheses

  5. Units of Analysis • Individual level: • Individuals, members of the parliament, individual laws, students in POL242 class • Typical in surveys: individual respondents • Aggregate level: • Countries, provinces, classes at U of T • Ecological fallacy: assuming something learned about an aggregate level phenomenon says something about the individuals in the aggregate unit • High income provinces vote for Liberals does not necessarily mean that rich people vote for Liberals

  6. Concepts • Concepts: ideas or constructs that represent real world phenomena • Democracy • Party affiliation • Social capital • Tolerance • Political conservatism • Social liberalism • Globalization

  7. Variables • Provide measurement of concepts • Contain different values • Examples: • Democracy variable can have the following values: • Democratic country • Non-democratic country • Political party affiliation in Canada variable can have the following values: • Conservative • Liberal • NDP • Other party

  8. Levels of Measurement In Theory In Practice Ordinal variables are often treated as similar to interval/ratio variables • Nominal • Ordinal • Interval/ratio

  9. Nominal Measure (Variable) • Nominal : A level of measurement describing a variable that has values that cannot be ranked in contrast to other types of variables • Examples of nominal measures: • Gender: Women and men cannot be ranked • Political party affiliation: Political parties cannot be ranked • Country: Countries cannot be ranked

  10. Ordinal Measure (Variable) • Ordinal : A level of measurement describing a variable with values we can rank-order along some dimension but cannot find the average value (the mean) • Examples: • education as composed of the following values: high school, university, post-graduate • socioeconomic status as composed of the following values: high, medium, low • religiosity as composed of the following values: very high, moderately high, moderately low, very low

  11. Interval/Ratio Measures (Variable) • Interval/Ratio: A level of measurement describing a variable whose values are rank-ordered and have equal distances between adjacent values • Examples: • Age (years) • Income • Percentage of vote for a presidential candidate

  12. Question • Which of the following are examples of nominal variables? • Religious affiliation (Catholic, Jewish, Muslim, Protestant, Other) • Race (Asian, Black, White, Other) • GDP per capita ($) • Education (years) • Defence spending as % of government budget • Socio-economic class (lower, working, middle, upper) • Grade (pass, fail)

  13. Measurement Reliability and Validity • Reliability: • Quality of measurement method that suggests that the same data would have been collected each time in repeated observations of the same phenomenon • Validity • A term describing a measure that accurately reflects the concept it is intended to measure

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