Representations Of Data

Question 1

Define an outlier:

Answer 1

An extreme value that lies outside the overall pattern of data

Question 2

Give 2 numerical definitions of an outlier:

Answer 2

Either greater than Q3 + k(Q3-Q1).

Or less than Q1 - k(Q3-Q1).

Question 3

Define an anomaly:

Answer 3

An outlier that is clearly an error so should be removed from the data (also known as cleaning the data).

Question 4

What do the 5 vertical lines in a box plot represent (starting from left to right)?

Answer 4

1) Lowest value that isn’t an outlier (boundary for outliers).
2) Lower quartile.
3) Median.
4) Upper quartile.
5) Highest value that isn’t an outlier.

Question 5

Where do the 4 horizontal lines go on a box plot (starting from left to right)?

Answer 5

First line connects the midpoint of first 2 vertical lines.
Next 2 lines connect top and bottom of 2nd, 3rd and 4th vertical lines, creating a rectangle with a vertical line in it.
Last line connects midpoint of 4th and 5th vertical lines.

Question 6

What do the crosses represent on a box plot and where do they go?

Answer 6

Represent outliers.

They either go to the left of first vertical line or to the right of last vertical line.