A knowledge of basic statistics is important for the researcher.

Describe your data:  

Total Number or "N", Mean, Median, Mode and Standard Deviation are used to describe your data. 

• The Total Number or "N" is the number of observations made.

• Mean:  This is the average of the data.  Adding the values of all of the observations and dividing the total by the total number of observations or "N".

• Median:  This is the middle value of the observations.  

• Mode:  This is the most frequent observation.

Thus for the data sequence of 2, 5, 7, 9, 10, 12, 12, 18, 20

• The "N" is 9

• The Mean is 10.33

• The Median is 10

• The Mode is 12

The Standard Deviation is a description of how tightly the observed data points are clustered around the mean.   One standard deviation should include approximately 68% of the data points.  Two Standard Deviations should include approximately 95% of the data points and three Standard Deviations should include approximately 99% of the data points. 

For the above example one Standard Deviation is 5.85.  

Microsoft Excel and Sun Microsystems's Open Office can calculate Standard Deviation and Means.    Download Open Office