Context:Reporting:pH

pH is defined over a logarithmic scale, and therefore cannot be averaged in the traditional manner. In Datashed's reports,

Median pH values are not shown because median pH is so easily misinterpreted.
Average pH is not calculated as a mean of pH values, but rather a mean of hydronium ion concentration:

$\mbox{Average pH} = - \log \frac{\sum_{i=1}^N 10^{-\mathrm{pH}_i}}{N}$