HW2 Grading Key (Biostat) Assigned 9/6; due 9/13; returned 9/20 [Answers to 2.3, 2.5A are online in their usual location]

Point value Key &comments
0  "Explore" output from lab -- enter name, mean age, and standard deviation into database; assign points next week
10 pts
stem
leaves
axis multiplier
shape
outlier
location
spread 
+ 3 free

(2.10A) IRISHWEB n = 46

08|0
09|
10|0
11|00
12|0
13|0000
14|000
15|0000000
16|0
17|00000000000000000000000
(�1)
Shape: negative skew; low potential outlier (8).
Central location: , Location(Median) = 23.5, Median = 17 
Spread: 8 to 17 or, if exclude the outlier 10 to 17. 

 

(2.10B) Table not shown to save printing space 

  (2.10C) 12 / 46 = .261 = 26.1%
 

(2.12A) PER-HISP.SAV (n = 50)
0|0001111111222222223333444445556677778899
1|035679
2|5
3|22
4|2
�10

(2.12B) Split stem
0|000111111122222222333344444
0|5556677778899
1|03
1|5679
2| 
2|5
3|22
3|
4|2
�10

(2.12C) The split stem does a better job of showing shape and potential outliers.
(2.12D) Shape: positive skew; outliers = 42 (New Mexico), 32 (California), 32 (Texas), 25 (Arizona)
Center: L(M) = 25.5; Median  = 4
Spread: from 0 to 42 (OK to exclude outliers, if you want to)