HW 1: Visualization and Markdown

Due by 11:59 PM on Sunday, February 7, 2021

For your first homework, you will practice using RMarkdown and ggplot2 on a dataset talking about animals and their sleep patterns.

Download the .Rmd template used for this homework here

Instructions

  • After completing the questions in your .Rmd, knit and upload both the .RMD and PDF or HTML files to Canvas.
  • Learning Outcomes
    • Choose appropriate graphics for exploratory data analyses.
    • Employ the ggplot2 system of visualization.

Hints

  • For this homework, we will use the msleep dataset from ggplot2.
  • Useful packages: ggplot2, ggthemes
  • Some useful functions: scale_fill_colorblind(), scale_y_log10(), facet_wrap(), scale_color_discrete(), geom_point(), ncol(), guides(), nrow(), ggplot(), geom_boxplot(), aes(), library(), data(), labs(),geom_smooth(), scale_x_log10(), theme_bw().

Grading Rubric {-}

Question.Part: Points Topic
1. .50 Loads packages and data
2. .50 Identifies numbers of mammals and variables
3.1 .50 Proper Question
3.2 .50 Response Variable and type
3.3 .50 Explanatory Variable and type
3.4 .50 Correct Plot Type
3.5 1.00 Correct Plot with data
3.6 .50 Interpretation
4.1 3.00 Three plots with transformed data
4.2 .50 Correct Interpretation
5.1 1.00 Color Coding
5.2 .50 Correct theme, labels and title
6.1 1.00 Correct OLS lines
6.2 .50 Interpretation
7.1 1.50 Box Plot with correct data and colors
7.2 .50 Correct scales
7.3 .50 No legend and correct colors and theme
8.1 2.00 Plot with correct data and facets
8.2 .50 Correct scales
8.3 .50 Correct line color
8.4 .50 Correct theme
EC.1 .50 Correct Overall OLS line
EC.2 .50 Interpretation
EC.3 .50 Correct Legend Title
Total 17 Plus 1.5 Optional Extra Credit

Question 1

Load the tidyverse and ggthemes packages and the msleep data set.

Question 2

How many mammals are in the msleep data frame? How many variables? Use two R functions to get this information.

Question 3

You want to explore if total sleep time has a relationship with mammal body weight.

  • Write out a question about the relationship
  • What is your response variable and what type is it?
  • What is your explanatory variable and what type is it?
  • What is the appropriate type of plot given the types of variables?
  • Create the appropriate plot with body weight against the total amount of sleep.
  • Interpret the plot in one sentence: what does the shape tell you about the relationship?

Question 4

When you see a curved or skewed relationship in a plot, you can often get rid of the curve or skew by taking a log transformation of either the explanatory or the response variable or both.

  • Create three plots: 1) ‘log(x), 2) log(y)and 3)log(x)andlog (y)`.
  • Which plot appears best (most linear) to you and why?

Question 5

Color code your preferred plot from question 4 by the diet of the animals (vore).

  • Make the axis labels nice,
  • Change the theme to your favorite theme_*(), and
  • Add a meaningful title to the plot.

Question 6

Copy the plot from part 5 and add an OLS(“lm”) line (without standard errors) for each vore category. Does the effect of body weight on sleep total appear larger for some diets?

Question 7

Reproduce the following plot:

Note the following elements:

  • the scale of the values of the y axis,
  • the lack of a legend,
  • the color scheme and the background.(hint: I used the colorblind safe palette)

Question 8

Reproduce the following plot:

Note the following elements:

  • the scale of the values of the x and y axes,
  • the facets,
  • the titles
  • the color of the line (doesn’t have to be an exact match),
  • the overall black and white theme

Extra Credit

Copy the plot from question 6 and add the overall (across all vore types) OLS line (without standard errors) to the plot.

  • Make sure this new line is dashed, and has width of 0.5.
  • Change the title of the legend to “Diet”.
  • In one sentence, how does this line compare to the individual lines?

Last updated on February 1, 2021

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