# Detecting the Speed Change Intention from EEG Signals:
## 3 Results
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#### 3.1.2 Cross-Validation Analysis of Electrode Configurations and Combined Features  
Among all the configurations tested and specific to E1, the best results for Single features of the six selected and Combination features are shown in Table 3 for each model type (Both, Increase and Decrease) and in different electrode configurations, depending on the feature. The values for the Combination features are higher than the Single features in general for each of the subjects and classifier models. For the average of subjects and models, Single features show an average accuracy of \(63.3\pm 11.6\%\), while the Combination of features shows a better average value of \(67.9\pm 10.9\%\). The largest difference between Single and Combination accuracies across subjects is shown in the model that uses only the Increase class with a difference in accuracy of 5.6%. This difference is in Decrease of 4.4% and in Both of 3.7%. The Combination configurations increase the results in all conditions, the average improvement was 4.6%  
The highest accuracy (see, Table 3) and the lowest standard deviation comparing Combination and Single feature classification in user average is shown in the Combination configuration for the Increase model, \(72.9\pm 8.6\%\). In second place Both \(66.1\pm 10.7\%\) and lastly Decrease \(64.8\pm 13.5\%\). Regarding the electrode configurations, the ratio of appearance of the computed configurations in Table 3 is as follows: the All electrode configuration appears 12 times, the Left appears 7 times, the Union appears 5 times, the Central appears 4 times and the Right appears 2 times. Based only on the Combination features, the Central electrode configuration, with an appearance ratio of 2, has an accuracy of 74.5%, while in second place the All, with an appearance ratio of 5, has an accuracy of 68.5%. The All electrode configuration is the most repeated in the Both and Increase models among all subjects and regardless of Single or Combination: it appears in Increase 6 times and in Both 4. In Decrease the Union electrode configuration is the most popular and appears 3 times. The band that appears the most in Table 3 is 23-30 Hz with a total of 19 times. The 8-14 Hz is selected 15 times, less than the 23-30 Hz even though 3 features are selected from the 8-14 band in the feature preselection (see Table 2). The one that appears the least was 15-22 Hz, a number of 11 times, but only 1 feature (\(HJ_{C}\)) is selected in this band in the preselection (see Table 2). The \(HJ_{A}\) feature is selected in Table 2 in fewer bands than the \(HJ_{C}\). However, going back to Table 3 and putting together the times, \(HJ_{A}\) appears in Single 9 and in Comb 12 times for a total of 21 times, slightly more than \(HJ_{C}\) that appears a total of 20 times. \(HJ_{C}\) is the second in appearance, with a high difference between the 16 times it appears in Comb \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **8–40 Hz** & **8–14 Hz** & **15–22 Hz** & **23–30 Hz** & **31–40 Hz** & **41–60 Hz** \\ \hline Pburg & - & 64.6 (1) & 58.9 (1) & - & - & - \\ EShnn & 58.3 (1) & 64.1 (1) & - & 61.8 (1) & 64.5 (2) & - \\ WP & 68.7 (2) & 64.5 (2) & 61.8 (3) & 60.9 (2) & 63.2 (2) & 63.7 (1) \\ HJ\({}_{A}\) & 61.6 (1) & **65.2 (3)** & 62.7 (2) & **63.0 (3)** & 68.4 (2) & 61.1 (1) \\ HJ\({}_{M}\) & 63.9 (1) & **64.2 (3)** & 64.8 (2) & 64.6 (1) & 61.6 (2) & 58.3 (1) \\ HJ\({}_{C}\) & 59.8 (1) & **63.0 (3)** & **63.8 (4)** & **63.6 (4)** & 61.8 (2) & 61.9 (3) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Average of the accuracy of the features that among all the models exceeded the established thresholds. In parentheses is shown the number of users it appeared. Selected features are in bold. If they did not pass the inclusion criteria, it was indicated with “-”. and in Single, only 4. \(HJ_{M}\) is by far the one that appears the least with only 4 times, 2 in single and 2 in Comb.