Error Analysis - EmSAT Achieve PDF Download

Introduction

• The purpose of making measurements is to determine the true value of a quantity. However, it is impossible to obtain the exact true value, and there will always be a certain level of uncertainty associated with measurements. This uncertainty represents the difference between a measurement reading and the true value.
• Measurement errors can be categorized into two types: random errors and systematic errors, both of which contribute to the overall uncertainty.

Random errors

• Random errors occur due to uncontrollable factors, such as variations in environmental conditions, and result in unpredictable fluctuations in the readings of an instrument. These errors affect the precision of measurements, causing a wider range of results around the mean value. To minimize random errors, it is recommended to perform multiple measurements and calculate the average of the results.

Systematic errors

• Systematic errors, on the other hand, arise from faulty instruments or flaws in the experimental method. These errors are consistent and repeatable, affecting the accuracy of all readings obtained using the same instrument or method. To reduce systematic errors, instruments should be recalibrated, or adjustments and corrections should be made to the experimental technique.

Another type of systematic error is known as zero error, which occurs when an instrument indicates a reading even when the true reading should be zero. This introduces a fixed error that must be taken into account when recording the results.

Precision & Accuracy

• Precision refers to how close the measured values are to each other. If repeated measurements yield similar or identical values, they can be considered precise. The precision of a measurement is reflected in the number of decimal places recorded, where measurements with more decimal places are considered more precise than whole number measurements.
• Accuracy, on the other hand, refers to how close a measured value is to the true value. By repeating measurements and calculating the mean average, the accuracy can be improved.