Sometimes one value in a series of repetitive measurements seems far out of line and we feel that perhaps a gross determinate error was made during that measurement. We intuitively want to discard it. The danger in subjective judgments about data is that we may reject a datum for which there has been no determinate error. One method for objectively determining if one measurement in a normally distributed data set is grossly in error is the Q-test. The value of Q you take from the table will depend on the number of observations and the percent of certainty you choose.
Students probably represent the largest group using the Q-test.
The tedium of calculating averages and standard deviations is relieved by using Excel. You can label these cells so that it is obvious what the values are. I usually place the labels to the left of the numbers and make them bold. One other tip on using equations in Excel. If you have a column of data and want to do the same calculation to each datum, enter the calculation for the first datum to the right, then copy that cell down the entire column.