Table 1.

Gaussian function fitting parameters for Figure 4. R² is the coefficient of multiple determinations for regression, which ranges from 0 to 1 and measures how close the data are to the fitted regression and how well the observed outcomes are replicated by the model. $\mu$ is an expected value, also known as the expectation, average, mean value, or first moment; and, ${\sigma }^2$ is an expectation variance value of the squared deviation of a random variable from its mean, also informally measuring how far a set of numbers are spread from their mean.

pH	R2	μ	${\mathit{\sigma }}^2$
6.0	0.9661	0.2021	0.152
7.0	1.0000	0.0230	0.165
8.0	0.9964	0.1756	0.217