comments on chapter 7

[lucysking]

1. When describing how to quantify SEM you write, "In general we have to be careful about doing this with smaller samples (less than about 30). Because we have many samples from the NHANES population and we actually know the population parameter, we can confirm that this works correctly by comparing the SEM estimated using the population parameter with the actual standard deviation of the samples that we took from the NHANES dataset." I'm not totally sure what you mean by "doing this" and "we can confirm that this works". Perhaps fill replace the "this" with your exactly what you're referring to?
2. You write, "The formula for the standard error of the mean says that the quality of our measurement involves two quantities:.." This is the first time you've mentioned "quality of measurement". I wonder if this should be mentioned right at the start of the chapter when you introduce sampling error? You could also there make it explicit that more sampling variability is bad and why with 1-2 sentences. Something like: "Sampling error and sampling variability are associated with the quality of our measurement of the population. Clearly, the larger the difference between our estimate and the population parameter, the worse our estimate is. Further, when there is greater variability in our estimates across samples we cannot know which estimate (if any) reflects the population parameter."
3. For the alcDist50 figure, I would set echo=FALSE as they won't know what the function means.

[poldrack]

#3 done.

[poldrack]

done, thanks!