Dixon test


To use the Dixon test the ratio is calculated:

Dixon 2

b = total range of measurements (here 14.1)

a= the distance between the part suspected of having an abnormal value and its nearest neighbour (here 8.6)

The ratio is calculated in %:

We then compare this ratio with the Dixon table:

Number of parts 3 5 10 16 20 30
 Maximum ratio 0.94 0.72 0.46 0.38 0.34 0.30


If the value is less than the maximum proposed ratio in the table then the value is not abnormal.  Here a ratio of 62% per 5 parts is less than 72%. The point is thus not an abnormal value.