This paper is from Session 8J: Evidence-based statistical practice
Full topic list
which comes under Topic 8: Research in statistics education

(Monday 12th, 14:00-16:00)

Understanding, teaching, and using p values



There are many problems with the p value. Is it an indicator of strength of evidence (Fisher), or only to be compared with α (Neyman-Pearson)? Many researchers and even statistics teachers have misconceptions about p, although p has been little studied, and we know little about how textbooks present it, and how researchers think about it, react to it, and use it in practice. The p value varies dramatically because of sampling variability, but textbooks do not mention this and researchers do not appreciate how widely it varies. I discuss the problems of p and advantages of confidence intervals, and identify research needed to guide the design of improved statistics education about p. I suggest the most promising teaching approach may be to focus throughout on estimation, use confidence intervals wherever possible, give p only a minor role, and explain p mainly as indicating where the confidence interval falls in relation to the null hypothesised value.