Stat 301 – Homework 1 answers
1. Text problem 1.8: survey of herbal medicine use in surgical patients
a) (2 pts) The 500 surgical patients are a sample because they are a subset of a larger population
consisting of all surgical patients in “several metropolitan hospitals across the country”.
Note: the problem never defines the population. This is common, which means you have to make an
intelligent guess.
b) (2 pts) Various answers are possible, depending on what you considered to be the population:
Yes, if the population is all surgical patients in the metropolitan hospitals used in the study.
Maybe, if the population is all surgical patients at metropolitan hospitals in the US (depends on
whether the study hospitals are representative of all metropolitan hospitals)
Probably not, if the population includes patients at rural hospitals or out-patient clinics
2. Text problem 1.17: MTBE contamination in NH wells
(no interpretations asked for in a, b, or c – all you need to provide are the figures)
a) (1 pt) Your choice of histogram (or something else we haven’t talked about if it describes the
distribution). Definitely your choice of how to draw that plot.
b) (1 pt)
c) (1 pt) (Note: the problem description defines “detectable level of MTBE as below limit or detect”)
d) (2 pts) (Note: lots of other formats possible for this plot!)
Public wells are more likely to be contaminated (MTBE detected) than are private wells.
3) Problem 1.21 with new questions: Honey as a cough remedy.
a) (3 pts, 1 for the plot, 2 for the conclusion) The side-by-side box plots are on the next page.
The honey treatment has the largest location (largest improvement in condition, largest total score)
b) (2 pts) The distribution of total scores in the honey treatment is reasonably symmetric. The
distances from the median to the quartiles or to the min or max of the data are approximately equal.
c) (2 pts)
Group
Mean
sd
Control
DM (Dextromorphan)
Honey
6.51
8.33
10.71
2.94
3.26
2.86
Note: Kelley’s rule would indicate reporting only one digit past the decimal point. That will be on the
next HW. I’m not concerned about digits this HW.
d) (2 pts). The DM treatment has the most variable scores. It has the largest sd.
e) (2 pts). The typical improvement on the Honey treatment is 11. (This is the median, which informs
you about the typical value for a subject in the group).