Ahmad Mousavi

Ahmad Mousavi

Assistant Prof. of Data Science,
Dept. of Math. and Stat.,
American University

Lab 14: Vectors and Iteration

DATA 412/612 · Week 14 · PDF · Source (.qmd)

Simulate a sampling distribution, then map models over diamonds.

Work in a Quarto document. Do notes 14.1 and 14.2 first.

library(tidyverse)

diamonds is in ggplot2. geom_hex() needs the hexbin package for the optional plot.

1. A sampling distribution

  1. Draw 1000 samples of size 30 from rexp(n = 30, rate = 1). Store the mean of each sample. Use a for-loop and pre-allocate the vector of means. Histogram the 1000 means.
  2. The same 1000 means with map_dbl().
  3. The same 1000 means with replicate().
  4. Repeat the replicate() version for n in c(5, 50, 100, 500). Histogram each set of means. Write two sentences about how the shape changes as n grows.

2. Diamonds

  1. Summary of every numeric column of diamonds with purrr, then again with across(). What is different about the two results?
  2. split() by color. Fit lm(price ~ depth) in each piece. Extract the p-value for depth and the adjusted R-squared.
  3. Optional: a hex plot of depth vs price, faceted by color, with an OLS line. Do the p-values and R-squared values match what the panels look like?