Errors in Measurement

Errors in measurement does not mean that the measurement is incorrect. It means that the measurement is not exact due to the measuring device or instrument.

The errors in measurement are classified into:

• Absolute error

• Relative error

• Percentage error

Absolute error is the difference between the actual value and measured value.

Absolute error

If the measured value is greater than the actual value, ignore the negative sign (-).

Relative error is the absolute error divided by the actual value.

Relative error

Percentage error is the relative error in percentage form.

Percentage error

Example 1
 (a) 0.017 kg
(b) 0.0069
(c) 0.69%

Step #1: Determine the actual value and the measured value.

The actual value is 2.467 kg and the measured value is 2.45 kg.

Step #2: Find the absolute error.

Absolute Error = Actual Value – Measured Value

= 2.467 kg – 2.45 kg

= 0.017 kg

Therefore, the absolute error is 0.017 kg.

Step #3: Find the relative error.

Relative Error = `text(absolute error) / text(actual value)`

Relative Error = `(0.017 kg)/(2.467 kg)`

Relative Error =` 0.0069`

Therefore, the relative error is `0.0069`.

Step #4: Find the percentage error.

Percentage Error = Relative Error x 100%

Percentage Error = 0.0069 x 100%

Percentage Error = 0.69%

Therefore, the percentage error is `0.69`%.

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