Update _01-sa-data-hello.qmd (#520)

Corrected the solution to Exercise 9b for Chapter 1, as "cases" is defined in the text as "unique observations". The 10 daycare centres are the experimental units.

Author: e-linc

exercises/_01-sa-data-hello.qmd

@@ -10,7 +10,7 @@
 1.  \(a\) Treatment: $10/43 = 0.23 \rightarrow 23\%$. (b) Control: $2/46 = 0.04 \rightarrow 4\%$. (c) A higher percentage of patients in the treatment group were pain free 24 hours after receiving acupuncture. (d) It is possible that the observed difference between the two group percentages is due to chance. (e) Explanatory: acupuncture or not. Response: if the patient was pain free or not.
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-1.  \(a\) Experiment; researchers are evaluating the effect of fines on parents' behavior related to picking up their children late from daycare. (b) 10 cases: the daycare centers. (c) Number of late pickups (discrete numerical). (d) Week (numerical, discrete), group (categorical, nominal), and study period (categorical, ordinal).
+1.  \(a\) Experiment; researchers are evaluating the effect of fines on parents' behavior related to picking up their children late from daycare. (b) 200 cases: the weekly observations of the 10 daycare centers over the 20 weeks. (c) Number of late pickups (discrete numerical). (d) Week (numerical, discrete), group (categorical, nominal), and study period (categorical, ordinal).
 \addtocounter{enumi}{1}
 
 1.  \(a\) 344 cases (penguins) are included in the data. (b) There are 4 numerical variables in the data: bill length, bill depth, and flipper length (measured in millimeters) and body mass (measured in grams). They are all continuous. (c) There are 3 categorical variables in the data: species (Adelie, Chinstrap, Gentoo), island (Torgersen, Biscoe, and Dream), and sex (female and male).