Formatting cleanup and studies table

[bpbond]

Hi @kendalynnm - I have tweaked thing to remove the ggplot 'formula = y ~ x' messages; reformatted the code for consistent style throughout (using the styler package); and made a few very minor changes for clarity.

The code functions identically to that in manuscript_Results.

[bpbond]

Added the requested studies table to this PR. I was a little unclear whether you wanted studies or observations...went with the former:

[kendalynnm]

This looks great Ben, thank you!