Accuracy stated conformance level measurement results to the price or the actual value; moderate accuracy states the degree of similarity in a group of measurement or number of instruments. Suppose we compare two voltmeter with models and from the same manufacturer. It should be the second voltmeter can be read with the same accuracy, but can also occur both the accuracy of the voltmeter can berbea altogether.
This can occur because of a system error in one of the voltmeter, eg changing tahaman sasalah one series in the voltmeter. Voltmeter to determine which ones produce a measuring error, required a comparison against a standard voltmeter (calibration). The accuracy consists of two characteristics, namely (1) the appropriateness, and (2) the number of significant digits of a measurement result.
Conformity is a requirement that is necessary but not sufficient to obtain the accuracy, suppose a prisoner 1.384572 mega-ohms measured by ohmmeter consistently and repeatedly gives the results of measurements of 1.4 mega-ohms. The question is whether these measures have read the actual price? Of course not, because we still need to discuss the meaning of numbers of the measurement results.
The figures, which means it provides actual information about the greatness and the accuracy of the measurement. The more meaningful numbers, the accuracy of measurement becomes greater. For example, if the value of a prisoner is 68 ohm, this means that these prisoners will be closer than 67 ohm 68 ohm or 69 ohm. Furthermore, if the mentioned resistance value is 68.0 ohms, meaning the resistance value should be more closer to 68.0 than 67.9 ohm ohm or 68.1 ohms.
At 68 ohm there are two numbers that mean, being in custody 68.0 ohms, which means there are three numbers, which have a higher accuracy than the prisoners 68 ohms. It was customary to record a measurement result by using all the numbers that we believe is closest to the actual price. For example, if a voltmeter read 117.1 volts; then this indicates that the assessment of the most well according to observers is closer to 117.1 volts than 117.0 volts or 117.2 volts.
Another way to express the results of measurements are using a summary of possible errors, so it can be written as 117.1 ± 0.05 volts. Example: A series of voltage measurements are performed consistently by the four observers provides measurement data: 117.02 volt, volt 117.11, 117.08 volts, and 117, 03 volts. Determine (1) the average value, and (2) rangkumankesalahan measuring. completion:
Summary of Errors (mak) = Umak – Urata with an average of 117.11 to 117.06 = 0.05 V
Summary of Errors (min) = Urata average – Umin = 117.06 to 117.02 = 0.04 V
Summary of average error = ± 0.045 = ± 0.05 V
It often happens that the number of digits is not necessarily express the precision of measurement. Large numbers with anka-zeros before the decimal point is often used in the assessment of the number of people or money. For example, if the population of a city is reported in the six figures, namely 380,000, this means that the actual population is between 379 000 and 380 001 which is in six figures mean.
But even in the six figures mean not 370,000 or 390,000 because the population is not closer to the figure of 380,000. Form of technical writing is more appropriate to use powers of ten, eg 38 x 104 or 3.8 x 105. Here, the population of just thoroughly until two significant figures. Uncertainty caused by the zeros on the left of the decimal point are usually treated with a mark of scientific writing is by using powers of ten.