Calculating Average Deviation

1. Find the average of your measurements.
2. Find the difference between the average and each of your measurements use absolute value.
3. Find the average of these differences.  This will be your deviation.

Example:

In the data set

2.10                      1. Find average               2. Find difference between
2.30                           24.26 ÷ 11 = 2.21            average and each      
2.22                                                                     measurement.
2.23                                                                    2.10 - 2.21 = .11
2.25                                                                    2.30 - 2.21 = .09
2.22                                                                    2.22 - 2.21 = .01
2.13                                                                    2.23 - 2.21 = .02
2.24                                                                    2.25 - 2.21 = .04 
2.28                                                                    2.22 - 2.21 = .01
2.17                                                                    2.13 - 2.21 = .08
2.22                                                                    2.24 - 2.21 = .03
                                                                            2.28 - 2.21 = .07
                                                                            2.17 - 2.21 = .06     
                                                                            2.22 - 2.21 = .01

                                3. Find the average of the
                                     differences
                                0.53 ÷ 11 = .05 (deviation)                                              

 Final answer for the data

2.21 ± .05