Occasionally one reads that the mean value of the pH values can be calculated via the geometric mean. The example with the 20 values from the calculator should show that this does not give correct results:

Values: 6.08 6.8 6.77 6.48 6.34 6.99 7.29 6.34 6.26 6.44 6.83 6.75 6.53 6.83 6.43 7.5 6.82 6.77 6.32 6.49 6.54

Outlier according to z-score analysis: 6.08

Comparison of different mean value procedures with and without consideration of the outlier

Mean:	arithmetic	pH	median	geometric	harmonic
with outlier	6.65	6.54	6.54	6.64	6.63
without outlier	6.68	6.58	6.65	6.67	6.66

Since the pH value is a logarithmic number, the seemingly small differences are not to be classified as irrelevant.