How to make a Box plot by hand:
1. Find the
5number summary (smallest value, Q1, Median, Q3, & the largest value)
2.
Construct a scale with values that include the minimum and maximum values
3.
Construct a box extending from the first quartile to the third quartile and
draw
a line in the box at the median value
4. Draw
lines extending outward from the box to the minimum and the maximum
data values and you're done!
How to make a Box Plot using the calculator: Put data into list #1:
Press STAT
Press ENTER (1:Edit)
Put in variable under list 1 L1
Press ENTER
(continue the last two steps until
you have added all of the variables in your list) Get the 5 number summary:
Press STAT
Press CALC
Press 1 (1: 1Var Stat)
Press 2^{nd}
Press L1 (or the name of the list
that you have put your information in) Press ENTER Press Down arrow (the last 5 things in the list are the 5 number summary)
To see the Box Plot: Press 2nd
Press Y= Press ENTER Press ENTER Press DOWN ARROW
Press RIGHT ARROW (till you highlight the box plot with the dots)
Press ENTER Press ZOOM PRESS 9 (9: zoom stat)
Voila! You have your box plot!
To find the Q1, Median, and Q3 by hand:  Put your data in a list from small to large
 Find the median (the value in the middle of the dataset)
 if there are 2 data values average them together to get the median
 Find the first and second Quartiles (Q1 & Q3) the same way:
 make 2 separate data sets and find the middle value of each new datasets.
 Find the Inter Quartile Range: Q3Q1
 Apply the Interquartile range to the formula below to ensure there are no outliers
 If there are outliers use the IQR (inter quartile range) to get the min and max values accepted as normal values
 Put any outliers on the plot as dots.
