# P-value

• ### Joke: The Psychic

A joke for discussing the over-use of hypothesis testing methods.  The joke was written in April 2019 by Larry Lesser from The University of Texas at El Paso.

• ### Song: Simulation!

A song to introduce the basic idea of using simulation to calculate a P-value for a randomization test (by simulating lots of group assignments and seeing what proportion of them give more extreme test statistics than observed with the actual group assignments).  The lyrics were written in November 2018 by Larry Lesser from The University of Texas at El Paso and Dennis Pearl from Penn State University. May be sung to the tune of the 1980 number #1 song “Celebration” by Kool and the Gang. Audio of the parody was produced and sung by students in the commercial music program of The University of Teas at El Paso.

• ### Collection: Statistical Calculators

Free statistical calculators online.  Our basic statistical calculators will help you in common tasks you might encounter and deal mostly with simple distributions.

• ### HyperStat Online: Ch. 9 The Logic of Hypothesis Testing

This chapter explains the structure/steps of hypothesis testing, the concept of significance, the relationship between confidence intervals and hypothesis testing, and Type I/II errors.

• ### Song: Everything's Unusual

A song for use in helping students to reason about how larger sample sizes decrease the p-value, all else being equal.  Lyrics by Larry Lesser and music by Dominic Sousa in 2015, both from The University of Texas at El Paso.  This song is part of an NSF-funded library of interactive songs that involved students creating responses to prompts that are then included in the lyrics (see www.causeweb.org/smiles for the interactive version of the song, a short reading covering the topic, and an assessment item).

• ### Analysis Tool: p-Value Analyzer (Shiny App)

This Shiny app implements the p-curve (Simonsohn, Nelson, & Simmons, 2014; see http://www.p-curve.com) in its previous ("app2") and the current version ("app3"), the R-Index and the Test of Insufficient Variance, TIVA (Schimmack, 2014; see http://www.r-index.org/), and tests whether p values are reported correctly.

• ### When does a significant p-value indicate a true effect? (Shiny App)

When does a significant p-value indicate a true effect?  This app will help with understanding the Positive Predictive Value (PPV) of a p-value.

This app is based on Ioannidis, J. P. A. (2005). Why most published research findings are false. PLoS Medicine, 2(8), e124. http://doi.org/10.1371/journal.pmed.0020124

• ### Analysis Tool: Distribution of Cohen's d, p-values, and power curves for an independent two-tailed t-test (Shiny App)

Plot the theoretical p-value distribution and power curve for an independent t-test based on the effect size, sample size, and alpha.

• ### Analysis Tool: Vovk-Sellke Maximum p-Ratio (Shiny App)

Explore the Vovk-Sellke Maximum p-Ratio, a measure that indicates the maximum diagnosticity of a given p-value. Choose your own p-value to find out how diagnostic it is for your research!

• ### Song: A Fitting Conclusion

A song for use in helping students to apply relationships among alpha, p-value, and the decision of a hypothesis test.  Music & Lyrics © 2015 by Lawrence M. Lesser from The University of Texas at El Paso.  This song is part of an NSF-funded library of interactive songs that involved students creating responses to prompts that are then included in the lyrics (see www.causeweb.org/smiles for the interactive version of the song, a short reading covering the topic, and an assessment item).