An apparatus for coaching improvements for a performer during a performance activity based on observed actual performance in comparison to a possible performance, with sensors measuring performance criteria. A microprocessor computer creates respective pseudo-measurements relevant to the performance activity based on the measurements, which are normalized and evaluated as to proximity to a possible performance value. A display presents the measured actual performance in relation to the possible performance, so the performer may change actions and observe on the display the effect of the change. A method of coaching performer during a performance activity is disclosed.