As a way of generating data with a spread about a central value, throw darts at the target (aiming for the central square) and record the number of hits within each square. Throw at least 100 darts, more if you have the patience. (The target is on the last page of this experiment.)
Add up the total number of hits on each row of the target.
Find the mean vertical position 
and the standard deviation 
.
Make a histogram of the y distribution and include on
the graph a normal distribution curve which has
the same values of and .
How well does this curve match your experimental distribution?
Is your value of at the center,
within the expected uncertainty?
(If it is not, does this mean that you are not aiming right?)
Now add up the total number of hits on each column of the target, and repeat the previous exercise for the x distribution.
You now have your accuracy in the vertical and horizontal directions
(by the numbers 
and ).
Why should you expect these two numbers to be, or not to be, the same?