Accuracy and Precision Flashcards
Characteristics of Analytical Procedures
Accuracy
Precision
Specificity
Detection Limit
Quantitation Limit
Linearity
Range
Robustness
Degree of agreement of test results with the true value, or the closeness of the results obtained by the procedure to the true value
Accuracy
The closeness of results that have been obtained exactly the same way; degree of agreememt among individual results
Precision
Expresses the precision obtained under the same operating conditions over a short interval of time
Repeatability/Intraassay precision
Expresses within laboratory variation, on different days, analyst, equipment
Intermediate precision
Precision between laboratory when a method is transferred from one part of a company to another
Reproducibility
The ability of the procedure to provide analytical results of acceptable accuracy and precision under variety of conditions
Robustness/Ruggedness ⭐
Considered during the development phase and show the reliability of an analysis when deliberate reliability are made in method parameters
Robustness/Ruggedness ⭐
The ability to produce results that are directly proportionnal to the concentration of the analyte in the samples
Linearity
Expression of the lowest and highest levels of analyte to be determinable for the product
Range
Ability to measure unequivocally the desired analyte in the presence od comoponents such as excipients and impurities
Specificity
The smallest quantity of an analyte that can be detected, and not necessarily determined
Detection Limit
The lowest concentration of an analyte in a sample that may be determined with acceptable accuracy and precision
Quantitation Limit
Indicated how responsive it is to a smalle change in the concentration of an analyte
Sensitivity
Accuracy is expressed in terms of
Absolute Error
Relative Error
Difference between the measured and the true value
Absolute Error
The measured value is the average of several measurements
Mean Error
Dividing the absolute error by true value
Relative Errors
Types of Errors in Analysis
Indeterminate Errors
Determinate Errors
Gross Errors
Slight variations in a series of observations made by the observer under identical conditions
Indeterminate Error / Random Error / Accidental Error
Errors difficult to detect, intangible, impossible to eliminate
Indeterminate Error
Source of Indeterminated Error
Analyst - difference in judgement and skill
Recur in a constant manner in series of determination, usually detectable, may be eliminated
Determinate Errors / Systematic Error
Sources of Determinate Errors
Personal Errors
Errors of Method
Apparatus/Instrumental Errors
