Book contents
- Frontmatter
- Contents
- Figures
- Tables
- Acknowledgments
- THE FUNDAMENTALS OF POLITICAL SCIENCE RESEARCH
- 1 The Scientific Study of Politics
- 2 The Art of Theory Building
- 3 Evaluating Causal Relationships
- 4 Research Design
- 5 Measurement
- 6 Descriptive Statistics and Graphs
- 7 Statistical Inference
- 8 Bivariate Hypothesis Testing
- 9 Bivariate Regression Models
- 10 Multiple Regression Models I: The Basics
- 11 Multiple Regression Models II: Crucial Extensions
- 12 Multiple Regression Models III: Applications
- Appendix A Critical Values of χ2
- Appendix B Critical Values of t
- Appendix C The Λ Link Function for BNL Models
- Appendix D The Φ Link Function for BNP Models
- Bibliography
- Index
7 - Statistical Inference
- Frontmatter
- Contents
- Figures
- Tables
- Acknowledgments
- THE FUNDAMENTALS OF POLITICAL SCIENCE RESEARCH
- 1 The Scientific Study of Politics
- 2 The Art of Theory Building
- 3 Evaluating Causal Relationships
- 4 Research Design
- 5 Measurement
- 6 Descriptive Statistics and Graphs
- 7 Statistical Inference
- 8 Bivariate Hypothesis Testing
- 9 Bivariate Regression Models
- 10 Multiple Regression Models I: The Basics
- 11 Multiple Regression Models II: Crucial Extensions
- 12 Multiple Regression Models III: Applications
- Appendix A Critical Values of χ2
- Appendix B Critical Values of t
- Appendix C The Λ Link Function for BNL Models
- Appendix D The Φ Link Function for BNP Models
- Bibliography
- Index
Summary
OVERVIEW
As researchers begin to consider possible tests of their theoretical propositions, they must make a series of important decisions. In this chapter we provide a discussion of choices of population and sample and inferences from samples about populations. We introduce this topic by using examples familiar to political science students – namely, the “plus-or-minus” error figures in presidential horse-race polls, showing where such figures come from and how they illustrate the principles of building bridges between samples we know about with certainty and the underlying population of interest.
How dare we speak of the laws of chance? Is not chance the antithesis of all law?
– Bertrand RussellPOPULATIONS AND SAMPLES
In Chapter 6, we discussed how to use descriptive statistics to summarize large amounts of information about a single variable. In particular, you learned how to characterize a distribution by computing measures of central tendency (like the mean) and measures of dispersion (like the standard deviation). For example, you can implement these formulae to characterize the distribution of income in the United States, or, for that matter, the scores of a midterm examination your professor may have just handed back.
But it is time to draw a critical distinction between two types of data sets that social scientists might use. The first type is data about the population – that is, data for every possible relevant case.
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- The Fundamentals of Political Science Research , pp. 120 - 133Publisher: Cambridge University PressPrint publication year: 2008