How do you find the accepted value in a percent error formula?

To determine the Percent value, you must have two variables: True value, the Recorded or Measured value, and it is represented by the following equation: (Recorded/Measured value - True value) /...

(actual yield-theoretical yield) / (theoretical yield)

That depends a lot on the application. In electronic circuits, an error of 5-10% or even more is often acceptable; for some applications, you need a much greater precision - even a millionth or less...

part over whole

Take the old value and subtract from the new value, then divide by the old value.Multiply by 100. That number representsthe percent change.