To do a statistical analysis you have to take your data and find
the following points from the data for each variable:
Minimum (lowest value)
Lower Quartile (middle value from the Median to the Minimum)
Median (middle value when all the data is lined up from least to
greatest)
Upper Quartile (middle value from the Median to the Maximum)
Maximum (Highest value)
To find the middle values just simply write all your data values
in order of least to greatest. Then you cross out the lowest value and the highest, then the second lowest and second
highest, and so on. Eventually you will arrive at a single number. That number is the middle value or Median.
If you arrive at two numbers then you take the average of the two.
Now you take the data and make a box and whisker plot. Basically
make a graph as if you were doing a bar graph. Then plot your Minimum, Lower Quartile, Median, Upper Quartile, and Maximum.
Make a box around the Lower Quartile, Median, and Upper Quartile. Do this for all your variables. Finally, compare
them. If the boxes overlap then there is not a statistical difference. If the boxes do not overlap then there is
a statistical difference.
That's all folks!
