Definition of Q test

1. The Q-test is a simple statistical test to determine if a data point that appears to be very different from the rest of the data points in a set may be discarded. Only one data point in a set may be rejected using the Q-test. The Q-test is:

   

   The value of Q is compared to a critical value, Qc.

   Table of Q critical values (90% confidence) N Qc 3 0.94 4 0.76 5 0.64 6 0.56 7 0.51 8 0.47 9 0.44 10 0.41

   If Q is larger than Qc the outlier can be discarded with 90% confidence. Related topics:

   • data handling