LABORATORY STATISTICS Flashcards
MEASURES OF CENTER/ central tendency
Mean, median, mode
average or arithmetic mean
Mean
midpoint of a data set after the values have been rank-ordered
Median
most frequently occurring value in a data set
Mode
MEASURES OF SPREAD/ Variability/ Distribution
Standard Deviation , Coefficient of Variation & Range
distribution of data points around the mean
Standard deviation
Square of SD
Variance
Best indicator of precision
Coefficient of variation
difference between the highest and lowest values
Range
Data points are distributed symmetrically around the mean (bell-shaped curve) with most values close to the center
GAUSSIAN/NORMAL DISTRIBURION
Mean, median, and mode are identical
GAUSSIAN/NORMAL DISTRIBURION
Empiric rule
68-95 - 99.7% rule
Rule of thumbs
CV = < 10 %
REFERENCE INTERVAL STUDIES
Verifying a reference interval & Establishing a reference interval
done when there is no existing RI for an analyte or when transference studies fail
Establishing a reference interval
Establishing a reference interval requires at least _______ study individuals; RI is set based on the ______________________
120; 95% confidence interval
CI = x̄ + /- 2s
done to confirm the validity of an existing or published RI for an analyte
Verifying a reference interval
Verifying a reference interval requires at least ____ study individuals; RI is adopted if _____ of the subjects fall outside the range
20; < 10%
first step in method evaluation; usually done by running two control materials twice a day over a 10-day period
Precision study
involves spiking a sample with a known amount of an analyte and determining how much of it can be detected by the method in the presence of other compounds in the matrix
Recovery study
compares the MEANS of two groups of data or the ACCURACY of two methods
T test
compares the STANDARD DEVIATION (SDs) of two groups of data or the PRECISION of two procedures
F test
used to compare two methods using the best fit line through the data points
Linear regression
Independent variable = reference method
X axis
Dependent variable = new method
Y axis
ability of a method to detect the smallest concentration of an analyte
Analytical sensitivity
ability of a method to detect only the analyte of interest
Analytical specificity
Diagnostic Efficiency
1) Diagnostic sensitivity
2) Diagnostic specificity
3) Positive predictive value
4) Negative predictive value
ability of a test to detect a given disease or condition; proportion of individuals with the disease who have a positive test result
Diagnostic sensitivity
ability of a test to detect the absence of a given disease or condition; proportion of individuals with no disease who have a negative test result
Diagnostic specificity
probability that a positive test result indicates disease; proportion of individuals with a positive result who truly have the disease
Positive predictive value
probability that a negative test result indicates absence of disease; proportion of individuals with a negative result who truly do not have the disease
Negative predictive value
management philosophy and approach that focuses on processes and their improvement as the means to satisfy customer needs and requirements
TOTAL QUALITY MANAGEMENT
Five Q Framework
Quality Planning (QP)
Quality Laboratory Process (QLP)
Quality Control (QC)
Quality Assurance (QA)
Quality Improvement (QI)
Quality Improvement Tools:
Six Sigma (6 σ) & Lean
Reduction of defects to near zero
Six Sigma (6 σ)
necessary to establish measures for performance monitoring, and ensure that the performance achieved satisfies quality requirements.
Quality planning
include analytical processes, general policies, practices, and procedures that define how all aspects of work are done.
Quality laboratory process (QLP)
involves statistical control procedures as well as nonstatistical checks
Quality control (QC)
concerned with broader measures of laboratory performance including TAT, patient identification, specimen collection, and test utility.
Quality assurance (QA)
provides a structured problem-solving process to help identify the root cause of a problem and a remedy for that problem.
Quality improvement (QI)
Reduction of non-valued activities (wastes)
Lean
Categories of wastes
Defects
Overproduction
Waiting
Non-utilized talent
Transport
Inventory
Motion
Excess processing
Steps in six sigma
DMAIC
Define
Measure
Analyze
Improve
Control
include test requisition, patient preparation, patient identification, specimencollection, labeling, specimen transport, specimen reception, handling, and preparation
Pre-analytical
include reagents, preventive maintenance of equipment, calibration, analysis of samples, and quality control
Analytical
include verification of calculations and reference ranges, flagging and notification of panic/critical values, delta checks, reporting of results
Post-analytical
an algorithm in which a current laboratory result is compared with results obtained on a previous specimen from the same patient
Delta check
Quality control
Reliability, accuracy, precision, internal quality control & external quality control
ability to maintain accuracy and precision over an extended period of time during which equipment, reagents, and personnel may change
Reliability
Closeness of the result to the true or actual value
Accuracy
Ability to produce a series of results that agree closely with each other
Precision
Commonly expressed in terms of coefficient of variation
Precision
Also call repeatability reproducibility
Precision
