subsection_Data_presentation_Noise_and__.tex

\subsection{Data presentation}

Noise and drift were calculated using all measurements except those with negligible boundary voltages, which were removed before processing. Unless stated otherwise, all data is presented as mean $\pm$ standard deviation across all measurements. Where applicable, the noise in repeated measurements is presented as three values, to aid comparisons to other systems in the literature: first as the standard deviation in absolute voltage, then as the ratio of the mean to standard deviation both as a percentage, and Signal-to-Noise ratio in dB. In accordance with previous studies, SNR was calculated differently for the triggered averaging experiment in the rat cortex. Instead the SNR was the ratio of the peak voltage change $\delta z$ following stimulation to the standard deviation before stimulus \cite{Oh2011}. The experimental setup for each experiment is summarised in table \ref{MSummary}.