information transfer rate
As a widely used metric in the BCI community, the ITR measures the performance of participants as well as classification algorithms by means of information theory. Taking into account the number of targets (M) and the average target selection time (T in seconds), the classification accuracy (P) can be converted to the ITR (in bits per min, bpm), which is defined as follows10 $ ITR=60\cdot \left({{\rm{\log }}}_{2}M+P{{\rm{\log }}}_{2}P+(1-P){{\rm{\log }}}_{2}\frac{1-P}{M-1}\right)/T (4)
Note that T includes the gaze time (e.g., 5 s) and the overall gaze shift time. For offline analysis, a gaze shift time of 0.5 s13 is usually set for validation and model comparison.