Quality Management, Quality Assurance, Quality Control Flashcards
quality control material
samples used for QC procedures designed to monitor analytical activity of a method by alerting the operator when there is a problem
- concentration is known
matrix
the substance used in QC which must be as close as possible to real humane species
run
finite time period or number of patient samples
Assayed control matieral
commercially prepared QC with a given specific mean and SD
unassayed control matieral
Commercially prepared QC naterial that **Does not have specific ranges verified by the manufacturer **
control limits
statistical criteria of acceptibility for particular control matieral, usually derived from the mean and SD
control rule
decision critera for judging a control material as acceptable or not
Westagard MultiRules
control chart
graphical method to display control results making it easier to determine if a control run is in our out of control
accuracy
describes how close a test is to the true value
expressed as %
helps identify systematic error
precision
refers to reproducibility of a test
expressed as %
helps to identify random error
systematic error
- problem in measurement that affects all measurements in the same way
- predicatble
- measured by accuracy
random error
- random events in the measurement process
- unpredictable
- measured by precision
levy - jennings graph
graph consisting individual data points plotted on a graph of the mean and the control limits of the particular control level
allows us to visualize QC across time
Shift
- consecutive oberservations above or below th emean
- representative of systematic error
- commonly accepted - 6 points on one side of the mean = shift
causes:
- improperly prepared reagents or controls
- change in lot numbers
- failure of an instrument
trend
slow change in QC values of either rising or falling steadily acorss several days or weeks (in relation to each other)
systematic error
causes:
- reagent or lamp deterioratin
- temp fluctuation
- calibration shift
R4s
one data point exceeding +2SD limit and nother data point exceeds -2SD limit (opposite directions)
2of3s2
2 of 3 points exceeding either +2SD or the -2SD limit on the same side
what testing factor has the most errors
preanalytical
pre analytical
factors involve collection, specimen transportation and time before testing
- proper labeling
- timing of speciment collection
- proper specimen transport and carrier and temperature
- speciment holding time
analytical factors
errors that occur during the testing phase
- instrument/ tech precision/accuracy
- calibration
- reagent status
- QC status
postanalytical facotrs
errors that occur after test is obtained bu before resultis posted to chart or sent to physician
- computer errors
- calculation errors
non analytical factors
errors not directly connected to the actual speciment testing, and more involved with the entire testing processs
- choosing approprate test
- hiring and training qualified staff
- instrument maintenance
trend
data rising or falling consistently
relation is to each othe, not the mean
shift
data consistently above or below the mean. relation is to the mean, not eachother.