25 Pictures of Point-Oh-Five

This chapter provides a gallery of plots that illustrate data sets where the calculated [latex]P[/latex]-value was exactly 0.05.

The aims of this gallery are threefold:

  • The pictures provide an overview of the various data types and analyses we have discussed in this book.
  • Each pair of plots contrasts a small sample size with a larger sample size and so the pictures clearly demonstrate the relationship between power and sample size across the various methods.
  • The pictures show you visually what life looks like on the threshold of the standard significance level.

Exercise 1

Create your own “pictures of point-oh-five”. You can use a table of random numbers to generate the data and adjust the effect size until the [latex]P[/latex]-value is 0.05.

Dot plots comparing two means

Dot plot comparing two means – [latex]n_1=n_2=10[/latex]
Dot plot comparing two means – [latex]n_1=n_2=100[/latex]

Box plots comparing two means

Box plot comparing two means – [latex]n_1=n_2=10[/latex]
Box plot comparing two means – [latex]n_1=n_2=100[/latex]

Density plots comparing two means

Density plot comparing two means – [latex]n_1=n_2=10[/latex]
Density plot comparing two means – [latex]n_1=n_2=100[/latex]

Scatter plots for a relationship between two continuous variables

Scatter plot for a relationship between two continuous variables – [latex]n=10[/latex]
Scatter plot for a relationship between two continuous variables – [latex]n=100[/latex]

Bar charts for a relationship between two categorical variables

Bar chart for a relationship between two categorical variables – [latex]n_1=n_2=100[/latex]
Bar chart for a relationship between two categorical variables – [latex]n_1=n_2=1000[/latex]

Scatter plots for logistic regression

Scatter plot for logistic regression – [latex]n=10[/latex]
Scatter plot for logistic regression – [latex]n=100[/latex]

Dot plots for comparing two main effects

Dot plots for comparing two main effects – [latex]n_{11}=n_{12}=n_{21}=n_{22}=25[/latex]
Dot plots for comparing two main effects – [latex]n_{11}=n_{12}=n_{21}=n_{22}=5[/latex]

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A Portable Introduction to Data Analysis Copyright © 2024 by The University of Queensland is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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