Quality Control

Quality Control

The application of statistical methods to evaluate the quality of products and services.

Sensitivity

The ability of an analytical method to measure the smallest concentration of the analyte of interest.

Specificity

The ability of an analytical method to measure only the analyte of interest.

Accuracy

The nearness or closeness of the assayed value to the true or target value.

Precision

The ability of an analytical method to give repeated results on the same sample that agree with one another.

Practicability

The degree to which a method is easily repeated.

Reliability

The ability of an analytical method to maintain accuracy and precision over an extended period of time.

Diagnostic Sensitivity

The ability of the analytical method to detect the proportion of individuals with the disease.

Diagnostic Specificity

The ability of an analytical method to detect the proportion of individuals without the disease.

Control Solutions (QC Materials)

Materials used to check the accuracy and stability of an assay.

Control Limits

Intervals of acceptable values with upper and lower limits used to determine if test results are accurate and precise.

Quality Assurance

A program focused on assuring the quality of products and services provided, including risk management, education, safety programs, and quality control.

Total Quality Management (TQM)

A management approach that emphasizes satisfying customer needs and continuous improvement.

Quality Assessment and Improvement (QA&I)

A continuous process of improving the system and meeting set goals and objectives.

Armand Feigenbaum

Coined the term total quality management.

Walter Shewhart

Known as the father of statistical quality control.

Philip Crosby

Preached the need for quality practices and "zero defects."

W

Introduced statistical tools and the concept of continuous improvement.

Joseph Juran

Established the concept of continuous improvement and the pareto principle.

James O

Applied multi-rule system to quality control data in the medical laboratory.

Accuracy

The closeness of a result to the actual value of an analyte.

Precision

The ability of an analytical method to give repeated results on the same sample that agree with one another.

Population

The items being studied at a particular time.

Sample

A part of a population used to analyze the characteristics of that population.

Gaussian Distribution

A bell-shaped curve that occurs when data elements are centered around the mean.

Probability

The likelihood of an event occurring, expressed as a decimal or percentage.

Mean

The arithmetic average of all the data in a sample population.

Median

The midpoint of a population when arranged from smallest to largest.

Mode

The most frequent observation in a dataset.

Standard Deviation

A measurement of precision, indicating how values cluster around the mean.

Orderly array of data

Refers to the procedure of arranging data from lowest to highest value, chronologically, by groups, etc.

Circle or Pie Charts

Circular figures used to represent the percentage of each component compared to the whole.

Bar graphs

Graphs used to present comparative factors between populations or within a population.

Line graphs

Graphs used to track and plot data over a period of time.

Histogram

A bar graph format used to show the relative size or frequency of each class interval.

Frequency polygons

Line graphs that display the frequency distribution of data, often referred to as a "bell curve."

Flow Chart

A visual representation used to identify and describe the sequence of work tasks and model alternative work routes.

Control Charts

Charts used to plot control measurements against standards to determine if a process is in or out of control.

Pareto Charts

Bar charts designed to illustrate the Pareto principle, which states that 80% of problems can be attributed to 20% of causes.

Cause-and-effect diagrams

Also known as Ishikawa or fishbone diagrams, used to identify possible causes or contributing factors of problems or defects.

Run charts

Line graphs used to display data over a period of time and show patterns of performance.

Scatter diagrams

Used to show the relationship between two variables.

Storyboards

Pictorial sequences used to visually present the story of a quality management project.

Levey-Jennings (L-J) chart

Widely used control chart in clinical laboratories to determine if a procedure is in or out of control.

Youden plot

Used to compare the performance of a laboratory on paired samples with other laboratories.

Multirule analysis

A set of rules proposed by Westgard and Barry for accepting or rejecting a control run based on the expected Gaussian distribution of sample values.

Random errors

Errors that occur unpredictably due to poor precision.

Systematic errors

Errors that occur predictably once a pattern is established.

Statistical bias

A set of numbers that do not truly reflect the characteristics of the whole population.

Outlier

Values that deviate significantly from the main set of values, caused by random or systematic error.

Skewed curves

Deviations from the symmetrical bell-shaped appearance of a frequency polygon, indicating data inaccuracies.

Trends

Systematic drift in one direction away from the established mean, observed through control values that consistently increase or decrease.

Dispersion

Widely scattered control values in an unusual and unexplained pattern around the control chart.

Shifts

Sudden switch of data points to another area of the control chart away from the previous mean.

External quality assessment programs

Programs initiated through the laboratory community, such as proficiency testing and accreditation, to assess the quality of laboratory performance.

Intralab Quality Control

Involves analyzing control samples together with patient specimens to monitor accuracy and precision of analytical methods.

Interlab Quality Control

Involves proficiency testing programs that provide samples of unknown concentration to participating clinical labs to maintain long-term accuracy.

Utilization Review

Hospital and physician review of the necessity of care to reduce patient length of stay.

Peer Review Organization

A federally mandated program that reviews hospital case records for quality of care and reimbursement decisions.

Critical-Care Pathways

A hospital-wide quality care management program that focuses on treatment outcomes as the definition of quality.