def stderr(predicted, actual):
return np.sqrt(mse(predicted, actual))<EOL>
Standard error of predictions.

.. versionadded:: 0.5.0

Parameters
----------
predicted : ndarray
    Predictions on which to measure error. May
    contain a single or multiple column but must
    match `actual` in shape.

actual : ndarray
    Actual values against which to measure predictions.

Returns
-------
err : ndarray
    Standard error of predictions relative to actual
    values.