2.7 Determining Signal-to-Noise Ratios at the Single Trial
Level
The signal-to-noise ratios were calculated for each component in the
STP, STW, and Averaged ERP approaches in order to determine if the SNR
for the STP approach would be similar to the other approaches.
Given that the baseline period is
not a flat line in single trials and rarely so even in averaged ERPs,
“noise” was calculated by obtaining the standard deviation of the
amplitude of all data points in the baseline period (i.e., -200 ms to 0
ms). The “signal” was the peak amplitude of each component. This
procedure is similar to the approach for determining a SNR value for
components in averaged ERPs (Debener, Ullsperger, Siegel, & Engel,
2006; Hu et al., 2010; Spencer, 2005).