Lec 1 Evaluation of Analytical Data

Significant Figures

The digits in a number that contribute to its precision, including all non-zero digits, any zeros between significant digits, and trailing zeros only when there is a decimal point.

Relative Uncertainty

The absolute uncertainty expressed as a fraction or percentage of the measured value, providing a sense of the uncertainty in relation to the size of the measurement.

Precision

The degree to which repeated measurements under unchanged conditions show the same results, indicating the reproducibility of the measurements regardless of their accuracy.

Difference Between Precision and Accuracy:

Precision refers to how consistently measurements can be replicated, while accuracy indicates how close those measurements are to the true or accepted value. 

A set of measurements can be precise (close together) but not accurate (far from the true value), or they can be accurate but not precise.

Random Error

Errors that arise from unpredictable fluctuations in measurements, which can vary in magnitude and direction, affecting the precision of results.

Accuracy

The degree to which a measured value reflects the true value of the quantity being measured, indicating how close the result is to the actual or accepted value.

Gross Error

aka "outliers", are errors other than random errors or systematic errors

Systematic Error

Consistent, repeatable errors associated with faulty equipment or flawed experimental design, which affect the accuracy of results by skewing them in one direction.

Absolute Uncertainty

The margin of uncertainty associated with a measurement, expressed as a fixed quantity (e.g., ±0.1), indicating the possible range of values around the measured value.