Book contents
- Frontmatter
- Dedication
- Contents
- Figures
- Tables
- Acknowledgements
- Getting Started
- Part I Why We Use Statistics
- Part II How to Use Statistics
- 5 Planning Your Statistical Analysis
- 6 A Cautionary Tail: Why You Should Not Do a One-Tailed Test
- 7 Is This Normal?
- 8 Sorting Out Outliers
- 9 Power and Two Types of Error
- 10 Using Non-Parametric Tests
- 11 A Robust t-Test
- 12 The ANOVA Family and Friends
- 13 Exploring, Over-Testing and Fishing
- 14 When Is a Correlation Not a Correlation?
- 15 What Makes a Good Likert Item?
- 16 The Meaning of Factors
- 17 Unreliable Reliability: The Problem of Cronbach’s Alpha
- 18 Tests for Questionnaires
- Index
11 - A Robust t-Test
from Part II - How to Use Statistics
Published online by Cambridge University Press: 26 January 2019
- Frontmatter
- Dedication
- Contents
- Figures
- Tables
- Acknowledgements
- Getting Started
- Part I Why We Use Statistics
- Part II How to Use Statistics
- 5 Planning Your Statistical Analysis
- 6 A Cautionary Tail: Why You Should Not Do a One-Tailed Test
- 7 Is This Normal?
- 8 Sorting Out Outliers
- 9 Power and Two Types of Error
- 10 Using Non-Parametric Tests
- 11 A Robust t-Test
- 12 The ANOVA Family and Friends
- 13 Exploring, Over-Testing and Fishing
- 14 When Is a Correlation Not a Correlation?
- 15 What Makes a Good Likert Item?
- 16 The Meaning of Factors
- 17 Unreliable Reliability: The Problem of Cronbach’s Alpha
- 18 Tests for Questionnaires
- Index
Summary
The t-test is a work horse of a lot of statistical analysis in HCI. There are a lot of myths about how robust it is to deviations from normality and other assumptions. However, when faced with practical data, particularly those coming from usability studies, the claims of robustness do not stand up. This chapter reevaluates the t-test as a test for an effect on the location of data. This leads to considering robust measures of location, such as trimmed or Winsorized means and associated Yuen–Welch test as a robust alternative to the traditional t-test.
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- Doing Better Statistics in Human-Computer Interaction , pp. 125 - 138Publisher: Cambridge University PressPrint publication year: 2019