Chapter 2: Describing Distributions w/Numbers

Question 1

Numerical summaries

Answer 1

• Measures of centre (mean, median)

- Measures of variation (range, quartiles, 5 #, variance, SD

Question 2

Location of median

Answer 2

L(M)=(n+1)/2

Question 3

Comparing mean and median

Answer 3

• Close when distribution is nearly symmetric
• Mean is more affected by outliers (good when you’re not concerned about distribution, like $/person)
• Median is outlier-resistant, more helpful for actually finding middle
• Decision depends on use, mean usually wins b/c it’s easier

Question 4

Point of quartiles/5 # summary

Answer 4

-Boils large set of data down into a few meaningful numbers

Question 5

Standard deviation

Answer 5

• Size of typical deviation f/mean

- First compute variance, then take square root