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Measurement of Error in Motor Behavior. Emily Wughalter, Ed.D . Error Measures. Error measures provide detail about performance accuracy in meeting a moving object in space. Error measures help to quantify performance. For example
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Measurement of Error in Motor Behavior Emily Wughalter, Ed.D.
Error Measures • Error measures provide detail about performance accuracy in meeting a moving object in space. Error measures help to quantify performance. • For example • As in swinging a bat and meeting a ball in space with the end of a bat • As in wanting to click on an icon by moving cursor on the screen • As in grabbing a stick of deodorant from the medicine cabinet • As in hitting a golf ball off a T, or in hitting the golf ball so that it is precisely directed in its flight and for its landing location • As in driving a car and being able to drive in a lane with acceptable variability
Measuring Error • Error measures are calculated to explain movement phenomena. They are calculated by applying varying algorithms. Error measures can help explain performance in matching personal movement to a moving or stationary object in space over a series of trials (trial blocks) . • Consider validity • Consider ecological validity • Consider reliability • Consider objectivity • Consider assumptions • Consider practical value and need
Three Error Measures in Motor Learning • Constant error • Variable error • Absolute error
Constant Error (CE) • CE provides information about a performer’s response bias • Does the performer generally respond early (undershoot) or late (overshoot) with respect to the target or matching location of a movement? • Does the performer have a general tendency? • CE is determined by adding up the algebraic error scores and dividing by the number of scores or calculating the mean. • CE should be presented with VE to more fully understand its meaning.
Variable Error (VE) • VE helps explain the changes or fluctuations in performance across a series of trials between a position in space and the matching of that position. • Calculate VE as the standard deviation of a set of scores (trial block)
Absolute Error • AE measures the average difference or average total error between the target location and the matching performance across a series of trials. • Calculate absolute error by obtaining the mean of the absolute value of the algebraic error scores for a series of trials.