Chapter 4

Question 1

range of data set

Answer 1

largest to smallest observation

Question 2

sample variance

Answer 2

s^2, sum of squared deviations from mean divided by n-1 and found w/ (refer to formula)

Question 3

standard deviation

Answer 3

s, positive square root of variance

Question 4

quartile

Answer 4

the three points that divide the data set into four equal groups, each group comprising a quarter of the data

Question 5

using random number generator

Answer 5

assign each person a number from 001 to 200, use RNG to pick X amount of people to use in sample. IMPORTANT: you may not repeat numbers!!

Question 6

why and how do we trim the mean of a sample?

Answer 6

a trimmed mean is computed by first ordering the data values from smallest to largest, deleting a selected # of values from each end & finally averaging remaining values. used when there are outliers or highly skewed date. trimming % is % of values deleted from each end

Question 7

boxplot

Answer 7

method of summarizing data that gives details to center and spread without being heavily influenced by outliers

Question 8

lower quartile

Answer 8

median of lower half of sample

Question 9

upper quartile

Answer 9

median of upper half of sample

Question 10

interquartile range (IQR)

Answer 10

upper quartile - lower quartile

Question 11

outlier

Answer 11

when observation is more than 1.5 IQR away from nearest quartile = mild. it’s extreme if more than 3 IQR from nearest end of box

Question 12

how to construct box plot

Answer 12

1. ) draw X axis (# line)
2. ) rectangle - left edge at Lower Quartile, right edge at Upper Quartile. the width is the IQR.
3. ) draw line inside at the median
4. ) whiskers from each end to smallest and largest observation in data

Question 13

how to modify box plot

Answer 13

1. ) determine any mild/extreme outliers
2. ) whiskers extend to most extreme observation that isn’t an outlier
3. ) solid circle for mild outlier
4. ) open circle for extreme outlier