chapter 12 feedback

[rpruim]

• "we use the cumulative density function" -> cdf = cumulative distribution function. That would be pnorm(), but you are using dnorm() throughout.
• It would be good to give a better description of what the numerator and denominator are in text rather than forcing the reader to sort it out by reading the code.
• Since augment() records residuals, you could use dnorm(.resid, 0, mean(.sigma, na.rm = TRUE)) to compute numerators and denominators.
• Fig 12.4: "Days with more values of wait_minutes_posted_avg farther from the mean appear to be downweighted" -> Days with more values of wait_minutes_posted_avg farther from the mean appear to be downweighted
• "Since we’re not using probabilities, we’ll calculate denominators for our weights from a normal density." -> This could use (more) motivation.
• "We then calculate the denominator using the dnorm()" -> This seems to be just restating the previous sentence, but it sounds like you are introducing a next/different step (then).
• eight and nine could be renamed to match scheme in other chapters. (Example: seven_dwarfs_9)