Q-Test

Q-test. Use to identify statistical outliers in data. This test should be applied sparingly and never more than once to a single data set.

R is the range of all data points, xa is the suspected outlier, and xb is the data point closest to xa. At the 90% confidence interval Q for N replicate measurements is:

Q-Test decision level at 90% confidence interval
N 3 4 5 6 7 8 9 10
Q 0.94 0.76 0.64 0.56 0.51 0.47 0.44 0.41