Transcript Error Measures

Error Measures
Emily Wughalter, Ed.D.
Error Measures
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Error measures help provide detail about performance
when meeting an object in space. They help to quantify
performance.
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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
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Error measures are determined to explain various
phenomena and by applying varying algorithms. They can
be used to explain performance for a series of trials (trial
blocks) with regard to matching a moving or stationary
object in space.
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Consider validity
Consider ecological validity
Consider reliability
Consider objectivity
Consider assumptions
Consider practical value and need
Error Measures in Motor Learning
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Constant error
Variable error
Absolute error
Constant Error (CE)
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CE provides information about a performer’s response
bias
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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)
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VE helps to explain the variability (changes) 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
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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.