Measurement Accuracy and Precision

These flashcards cover key concepts related to measurement accuracy and precision, types of errors, and methods for ensuring reliable and valid measurements.

Central Value

The central value of a set should be determined, indicating the main measurement from a group of data.

Accuracy

Indicates the closeness of the measurement to the true or accepted value.

True Value

Typically unknown value that measurements aim to approximate.

Precision

The agreement among several results obtained in the same way.

Standard Deviation

A statistical measure that expresses the amount of variation or dispersion in a set of values.

Variance

The square of the standard deviation, representing the degree of spread in data.

Coefficient of Variation

A standardized measure of dispersion of a probability distribution.

Indeterminate Error

Errors that cause measured values to scatter randomly about the mean and cannot be corrected.

Determinant Error

Errors that have a definite value and assignable cause.

Systematic Errors

Errors that lead to bias and have the same magnitude for replicate measurements.

Gross Error

Significant errors that deviate far from accepted standards.

Random Error

Inconsistent errors that cannot be easily identified or corrected.

Figures of Merit

Derived numerical values used to evaluate the performance of an instrument or technique.

Bias

A systematic deviation of the measured value from the true value.

Sensitivity

The ability of a measurement to detect small changes or differences.

Detection Limit

The lowest quantity of a substance that can be reliably detected.

Dynamic Range

The range of input values over which an instrument or measurement system can operate effectively.

Selectivity

The ability to detect a specific analyte in the presence of other substances.

Linearity

The degree to which a measurement is directly proportional to the value being measured.

Statistical Methods

Mathematical techniques applied to data analysis to interpret results.

Replicate Measurements

Repeated measurements taken to improve reliability and minimize errors.

Measurement Uncertainty

The doubt that exists regarding the result of a measurement.

Mean Value

The average of a set of measurements, calculated by summing all values and dividing by the total number.

Random Scattering

The distribution of measured values around the mean due to indeterminate errors.

Impact of Indeterminate Errors

Indeterminate errors lead to unpredictable variations that affect measurement results.

Characterization of Systematic Errors

Systematic errors have an assignable cause and can skew results consistently.

Instrumental Errors

Faults arising from the instruments used in measurement.

Method Errors

Errors resulting from the method or technique employed in taking measurements.

Personal Errors

Variability introduced by the individual taking the measurement.

Measurement Replicates

Samples carried through analysis in exact conditions to improve reliability.

Correcting Systematic Errors

Systematic errors can be identified, traced, and corrected for improved accuracy.

Use of Averaging

Averaging multiple measurements can help reduce the effects of indeterminate errors.

Causes of Measurement Error

Errors arise from a variety of sources, including instrument limitations, operator mistakes, and environmental factors.

Importance of Reliability

Measurements must be repeatable and consistent to be considered reliable.