First look at Palmer Penguins (Complete)

Data visualization and transformation
Data Science with R

Introduction

How do bill sizes of penguins vary across species? And what happens if we don’t take species into consideration?

Packages

We will use the tidyverse packages for data wrangling and visualization and the palmerpenguins package for the data.

library(tidyverse)
library(palmerpenguins)

Data

The dataset we will visualize is called penguins. Let’s glimpse() at it.

glimpse(penguins)

Rows: 344
Columns: 8
$ species           <fct> Adelie, Adelie, Adelie, Adelie, Adelie, Adelie, Adel…
$ island            <fct> Torgersen, Torgersen, Torgersen, Torgersen, Torgerse…
$ bill_length_mm    <dbl> 39.1, 39.5, 40.3, NA, 36.7, 39.3, 38.9, 39.2, 34.1, …
$ bill_depth_mm     <dbl> 18.7, 17.4, 18.0, NA, 19.3, 20.6, 17.8, 19.6, 18.1, …
$ flipper_length_mm <int> 181, 186, 195, NA, 193, 190, 181, 195, 193, 190, 186…
$ body_mass_g       <int> 3750, 3800, 3250, NA, 3450, 3650, 3625, 4675, 3475, …
$ sex               <fct> male, female, female, NA, female, male, female, male…
$ year              <int> 2007, 2007, 2007, 2007, 2007, 2007, 2007, 2007, 2007…

Penguin bills

Create a scatterplot of bill_depth_mm vs. bill_length_mms of penguins. Overlay a line of best fit. Describe the relationship between the two variables.

ggplot(penguins, aes(x = bill_length_mm, y = bill_depth_mm)) +
  geom_point() +
  geom_smooth(method = "lm", se = FALSE)

`geom_smooth()` using formula = 'y ~ x'

Warning: Removed 2 rows containing non-finite outside the scale range
(`stat_smooth()`).

Warning: Removed 2 rows containing missing values or values outside the scale range
(`geom_point()`).

There is a negative relationship between bill depth and bill length. The relationship is somewhat weak and linear.

Create a scatterplot of bill_depth_mm vs. bill_length_mms of penguins, colored by species. Overlay a line of best fit. Describe the relationship between the two variables for each of the species.

ggplot(penguins, aes(x = bill_length_mm, y = bill_depth_mm, color = species)) +
  geom_point() +
  geom_smooth(method = "lm", se = FALSE)

`geom_smooth()` using formula = 'y ~ x'

Warning: Removed 2 rows containing non-finite outside the scale range
(`stat_smooth()`).

Warning: Removed 2 rows containing missing values or values outside the scale range
(`geom_point()`).

There is a positive relationship between bill depth and bill length for each of the three species. The relationships are moderately strong and linear.

Reflect on the seemingly contradictory findings from the two visualizations you’ve created. Which one do you believe more, and why?

I believe the second one more, we should be considering species when analyzing the relationship between bill depth and bill length for penguins.