Relative Positions of Data and Boxplots (a.k.a. Quartiles (2)!)

Question 1

It cuts the data into two so that
- approximately P% of the data lie below it and
- approximately (100-P)% of the data lie above it

Three of these that cut the data into fourths would then be called quartiles.

Answer 1

Percentile

Question 2

How do you split the data set when the number of data points is EVEN? What about when it is ODD?

Answer 2

EVEN: Exactly in half
ODD: Include the median in both halves

Question 3

What is the relationship between the boxplot and the five-number summary?

Answer 3

The five-number summary are the set of numbers/values needed to create the boxplot that would represent the data

Question 3

It is the length of the interval that contains the middle half of a numerically arranged data set

Answer 3

Interquartile range (IQR)

Question 4

Observations which are far unusually different/far from the bulk of the data

Answer 4

Outliers

Question 5

What are the formulas for the two types of outliers?

Answer 5

1. Less than Xmin [Q1 - (1.5 X IQR)]
2. Greater than Xmax [Q3 + (1.5 X IQR)]

Question 6

It shows the distance of a value (x) from the mean of the data set in standard deviation units

Answer 6

Z-score

Question 7

What does a negative and positive z-score represent?

Answer 7

Negative - the observation is below average
Positive - the observation is above average