Chapt 5 Flashcards
a system of ensuring accuracy and precisions in the laboratory
a process ensuring that analytical results are correct by testing known samples tat are resemble patient sample
quality control
involves in the process of monitoring the characteristics of the analytical process and detect analytical errors during testing and ultimately prevent the reporting of inaccurate patient test results
quality control
measures the smallest concentration of an analyte of interest
sensitivity
determines only the analyte of interest
specificity
the nearness or closeness of the assayed value to the tru or target value
accuracy
the capacity of the assay to give repeated results on the same sample that agree with one another
precision or reproductibility
the degree by which a method is easily repeated
practicability
achieved when the assay is able to maintain accuracy and precisions over an extended period of time during which equipment, reagents, personnel may change
reliability
detects the proportion of an individuals WITH the disease
diagnostic/assay sensitivity
detects the proportion of an individuals WITHOUT the disease
diagnostic/assay specificity
the method to differentiate correctly whose individual with the disease against healthy cases utilizing the proportion of true positive and true negative in all evaluated cases
diagnostic/assay accuracy
define the parameters in the calculation
True Positive (T+): CORRECTLY identifies as a PATIENT
False Positive (F+): INCORRECTLY identifies as a PATIENT
True Negative (T-): CORRECTLY identifies as a HEALTHY
False Negative (F-): INCORRECTLY identifies as HEALTHY
what are the objectives of quality control
- to check the stability of the machine
- to check the quality of the reagents
- to check technical errors
the analysis of control samples together with the patient specimens
Intralab QC
detects changes in performance between the present operation and the stable operation
Intralab QC
involves proficiency testing programs that periodically provide samples of unknown concentration to participating clinical laboratories
Interlab QC
maintains long-term accuracy of the analytical methods
Interlab QC
differentiate commutable reference sample and non-commutable reference sample
commutable: relates to the closeness of agreement between the results for an RM and results for clinical samples when measured by more than or equal to two measured procedures
non-commutable: will have a measurement bias for clinical samples and results will not be compared across all processes
achieved by an unknown sequence of calibrations, using reference that must be commutable
Traceability
these are errors encountered in the collection, preparation and measurement of samples, including transcription an release of laboratory results
variation
an error present in all measurement, is due to chance
the bias for varying differences between repeated measurements
Random error
an error that influences observations consistently in one direction
detects either positive or negative bias
systemic error
and error refers to the difference between the target value and the assayed value
exist when there is a continual difference between the comparative method and the test method regardless of the concentration
constant error
and error that results in greater deviation from the target value due to higher sample concentration
exist when the difference between test method and comparative method is proportional to the analyte concentration
proportional/slop/percent error
activities that takes place before testing
pre-analysis
comprises patient reporting and result interpretation
post-analysis
