Mean:  This is simply the arithmetic average.  Add up all the cases, and divide by the number of cases.
Median:  This is the case in the middle.  Put all the cases in order, then select the one in the middle.  If you have an even number of cases, choose the point midway between the two closest to the middle.
Expected Frequencies:  Prepare a cross-tabulation table with row totals (rt), column totals (ct) and a grand total (gt).  The expected frequency for each cell is rt * ct/ gt.
Standard Deviation: Use the formula at the right:

As an algorithm (a set of steps to be followed in sequence):

1.  If you have not yet calculated the mean, do so.

2  Set up a table with four columns and a row for each case:

3.  Enter X, the value for each case, in the first column.

4.  Put the mean in the second column, it is the same for each row.

5.  For each case, subtract the mean from the value for the case and enter the result in the third column

6.  Square the result in the third column and put it in the fourth column.
 

X = Each Score	The Mean	X - the Mean	X-the mean squared
.	.	.	.
.	.	.	.
.	.	.	.
.	.	.	.
.	.	.	.

7.  Now add up the fourth column, this is the Sum of Squares.  Write it here:  .        .

8.  Divide the sum of squares by the number of cases, minus one (N-1).  This is the variance.  Write it here: .        .

9.  The standard deviation is the square root of the variance.  Write it here: .         .