Appex 10

STA 112 - Fall 2023

Part 1

1. Create a new project from this template in RStudio Pro:

https://github.com/sta-112-f23/appex-10.git

2. Load the packages and data by running the top chunk of R code
3. Learn about the USstamps data by running ?USstamps in your Console
4. Use the filter function to remove observations with Year less than 1958
5. Fit a linear model predicting the stamp price from year
6. Calculate the studentized residuals and plot them – are there any outliers?
7. If you found an outlier, refit the model without it – is this point “influential”?

Part 2

1. Go to https://lucy.shinyapps.io/magnolia-data/
2. “Measure” 30 leaves by clicking on on 30 leaves in the photo of the Mag Quad.
3. Copy the code on the right and paste it in your appex-10.qmd file. Run the code to create a data frame called magnolia_data
4. Fit a linear model predicting leaf length from leaf width from your magnolia data. What is your estimate for \(\hat\beta_1\)? Create a confidence interval for this estimate.