Statistics: nth percentile
Hi, MHF :) I'm taking stats this semester, and my answer differs from my book's.
I am using software called R (The R Project for Statistical Computing)
My book uses software called Minitab (Statistical Analysis: Data Analysis and Statistics Software and Training | Minitab)
I have two sets of data, one for a group with a high dose of some medicine, and one for the control group:
High = 16.1 , 134.9 , 52.7 , 14.4 , 124.3 , 99.0 , 24.3 , 16.3 , 15.2 , 47.7 , 12.9 , 72.7 , 126.7 , 46.4 , 60.3 , 23.5 , 43.6 , 79.4 , 38.0 , 58.2 , 26.5 , 25.1
Control = 297.1 , 491.8 , 1332.9 , 1172.0 , 1482.7 , 335.4 , 528.9 , 24.1 , 545.2 , 92.9 , 337.1 , 102.3 , 255.1 , 100.5 , 159.9 , 168.0 , 95.2 , 132.5 , 442.6 , 15.8 , 175.6 , 131.1
I need to find for each group:
a) sample mean, variance, and standard deviation
b) sample upper and lower quartiles
c) sample median
d) construct a boxplot
e) 5th and 95th percentiles.
Here are my answers, green implies they agree with the book. Red implies they disagree, and the book's answer will be adjacent.
High Dose:
Sample mean: 52.65
Sample variance: 1490.315
Sample standard deviation: 38.6046 (not given in the book)
Upper Quartile: 69.60 (book: 74.38)
Lower Quartile: 23.70 (book: 21.70)
Sample median: 45.00
5th percentile: .05(22+1) = 1.15 || 1st = 12.9 || 2nd = 14.4 || (12.9+14.4)/2 = 13.65 (book: 13.125)
95th percentile: .95(22+1) = 21.85 || 21st = 126.7 || 22nd = 134.9 || (126.7+134.9)/2 = 80.8 (book: 133.67)
Control:
Sample mean: 382.7
Sample variance: 175224.4
Sample standard deviation: 418.5981 (not given in book)
Upper Quartile: 479.5 (book: 501.1)
Lower Quartile: 109.5 (book: 101.9)
Sample median: 215.3 (book: 215.4 -- probably different rounding rules in our software)
5th percentile: .05(22+1) = 1.15 || 1st = 15.8 || 2nd = 24.1 || (15.8+24.1)/2 = 19.95 (book: 17.045)
95th percentile: .95(22+1) = 21.85 || 21st = 1332.9 || 22nd = 1482.7 || (1332.9+1482.7)/2 = 1407.8 (book: 1460.23)
Can anyone help me figure out why my answers are incorrect?
Thank you.
