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R2
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Definition
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The correctness metric for the Non-human Primate Motor Prediction task.

During evaluation, the coefficient of determination (:math:`R^2`) for the :math:`X` and :math:`Y` velocities are averaged to report the correctness score for each session, where :math:`n` is the number of labeled points in the test split of the session, :math:`y_i` is the ground-truth velocity, :math:`\hat{y_i}` is the predicted velocity, and :math:`\bar{y}` is the mean of the ground-truth velocities. The :math:`R^2` from sessions for each NHP are averaged, producing two final correctness scores.

.. math::
    R^2 = 1 - \frac{\sum_{i=1}^{n} (y_i - \hat{y_i})^2}{\sum_{i=1}^{n} (y_i - \bar{y})^2}

Implementation Notes
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This is a two-dimensional implementation of R2.