MATH 315 Exam 01 Practice

Due 2025-09-29 by 12:51pm

Please submit Exam 01 Practice just like you would a homework assignment

  1. Use the function read.csv to read in the dataset found at the following URL

    https://raw.githubusercontent.com/roualdes/data/refs/heads/master/horse_prices.csv

    The dataset is about horses and their prices and has a help file.

  2. What type of study did these data likely come from? Why?

  3. Load the libraries ggplot2 and dplyr.

  4. What are all the variable types?

  5. Identify reasonable explanatory and response variables (one of each). Be specific about which is which and why.

  6. Make a histogram of a variable of your choice.

  7. Calculate the mean and median for the same variable from question 6. above. Explain why the shape of the data in the histogram above makes sense relative to the values of the mean and the median.

  8. Use ggplot to make a boxplot (multiple boxes). Write one or two complete English sentences describing the plot, using keywords from this class. You should use at least quantile/quartile, interquartile range, and mean.

  9. Calculate the summary statistics mean, std, and number of data n, of some numerical variable grouped by a categorical variable of your choice. Write two complete English sentences describing these summary statistics in context of the data.

  10. For each part, compare the datasets 1. and 2. below, based on means and standard deviations. Which, if any, has the larger mean? Which, if any, has the standard deviation? Explain your answers.

    a.

    1. 3, 5, 5, 5, 8, 11, 11, 11, 13
    2. 3, 5, 5, 5, 8, 11, 11, 11, 20

    b.

    1. -20, 0, 0, 0, 15, 25, 30, 30
    2. -40, 0, 0, 0, 15, 25, 30, 30