Book contents
- Frontmatter
- Contents
- List of figures
- List of tables
- List of boxes
- Introduction
- Part I Effect sizes and the interpretation of results
- 1 Introduction to effect sizes
- 2 Interpreting effects
- Part II The analysis of statistical power
- Part III Meta-analysis
- Last word: thirty recommendations for researchers
- Appendices
- Bibliography
- Index
1 - Introduction to effect sizes
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- List of figures
- List of tables
- List of boxes
- Introduction
- Part I Effect sizes and the interpretation of results
- 1 Introduction to effect sizes
- 2 Interpreting effects
- Part II The analysis of statistical power
- Part III Meta-analysis
- Last word: thirty recommendations for researchers
- Appendices
- Bibliography
- Index
Summary
The primary product of a research inquiry is one or more measures of effect size, not p values.
~ Jacob Cohen (1990: 1310)The dreaded question
“So what?”
It was the question every scholar dreads. In this case it came at the end of a PhD proposal presentation. The student had done a decent job outlining his planned project and the early questions from the panel had established his familiarity with the literature. Then one old professor asked the dreaded question.
“So what? Why do this study? What does it mean for the man on the street? You are asking for a three-year holiday from the real world to conduct an academic study. Why should the taxpayer fund this?”
The student was clearly unprepared for these sorts of questions. He referred to the gap in the literature and the need for more research, but the old professor wasn't satisfied. An awkward moment of silence followed. The student shuffled his notes to buy another moment of time. In desperation he speculated about some likely implications for practitioners and policy-makers. It was not a good answer but the old professor backed off. The point had been made. While the student had outlined his methodology and data analysis plan, he had given no thought to the practical significance of his study. The panel approved his proposal with one condition. If he wanted to pass his exam in three years' time he would need to come up with a good answer to the “so what?”
- Type
- Chapter
- Information
- The Essential Guide to Effect SizesStatistical Power, Meta-Analysis, and the Interpretation of Research Results, pp. 3 - 30Publisher: Cambridge University PressPrint publication year: 2010
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