Statistical tests

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1 Task

Note

Find the solution here.

1.1 Get started

We will again use the penguins tibble from the palmerpenguins package for this task.

So before you get started with the exercise, make sure that you load the palmerpenguins package and the tidyverse

library(palmerpenguins)
library(tidyverse)

1.2 Compare the flipper length of penguins using statistical tests

Question: Does the mean flipper length differ between the 3 penguin species?

Do separate comparisons for

• Gentoo vs. Adelie
• Gentoo vs. Chinstrap
• Adelie vs. Chinstrap

Before you start, create a subset of each species as a vector.

For this, you can use the $ operator:

adelie <- filter(penguins, species == "Adelie")$flipper_length_mm
chinstrap <- filter(penguins, species == "Chinstrap")$flipper_length_mm
gentoo <- filter(penguins, species == "Gentoo")$flipper_length_mm

Follow the decision tree for statistical tests:

1.3 Extra

Create a plot to show the results of your tests. Choose one of the following:

• Create a boxplot with notches to visually compare differences in flipper length between species
• Make a plot showing the mean and standard error of the mean as pointrange or point with errorbars

Add a geom_signif() layer to the plot you just created to indicate your test results