Failing Grade: 89% of Introduction-to-Psychology Textbooks That Define or Explain Statistical Significance Do So Incorrectly. Issue 3 (September 2019)

• Record Type: Journal Article
• Authors: Cassidy, Scott A.; Dimova, Ralitza; Giguère, Benjamin; Spence, Jeffrey R.; Stanley, David J.
• Is Part Of: Advances in methods and practices in psychological science. Volume 2:Issue 3(2019)
• Page Start: 233
• Page End: 239
• Publication Date: 2019-09
• Subjects: p values -- null-hypothesis significance testing -- statistical inference -- quantitative literacy -- quantitative psychology -- open data -- open materials; Psychology -- Periodicals; Psychology -- Research -- Periodicals; 150
• DOI: 10.1177/2515245919858072
• Languages: English
• ISSNs: 2515-2459

Abstract

Null-hypothesis significance testing (NHST) is commonly used in psychology; however, it is widely acknowledged that NHST is not well understood by either psychology professors or psychology students. In the current study, we investigated whether introduction-to-psychology textbooks accurately define and explain statistical significance. We examined 30 introductory-psychology textbooks, including the best-selling books from the United States and Canada, and found that 89% incorrectly defined or explained statistical significance. Incorrect definitions and explanations were most often consistent with the odds-against-chance fallacy. These results suggest that it is common for introduction-to-psychology students to be taught incorrect interpretations of statistical significance. We hope that our results will create awareness among authors of introductory-psychology books and provide the impetus for corrective action. To help with classroom instruction, we provide slides that correctly describe NHST and may be useful for introductory-psychology instructors.