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 Measurement Reliability and Validity 2

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 3

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 4

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 5

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

Variables Provide measurement of concepts Contain different values Examples: Democracy variable can have the following values: 1.Democratic country 2.Non-democratic country Political party affiliation in Canada variable can have the following values: 1.Conservative 2.Liberal 3.NDP 4.Other party 7

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

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

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

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

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

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 14