MTBF (Mean Time Between Failures)

MTBF is the average elapsed time between failures in a repairable system. It is calculated by dividing the total operational time by the number of failures encountered. MTBF is a key reliability metric used to predict system performance and plan for maintenance.
See also: Reliability Engineering, Preventive Maintenance

MTTF (Mean Time To Failure)

MTTF is the average time expected until the failure of a non-repairable system or component. It represents the inherent lifespan of a product under normal operating conditions and is commonly used for products that are not intended to be repaired after failure.
See also: Reliability Analysis, Life Testing

MTTR (Mean Time To Repair)

MTTR is the average time required to repair a failed component or system and restore it to full functionality. It includes repair time, testing, and any necessary adjustments to return the system to normal operation.
See also: Downtime Analysis, Maintenance Planning

Maintenance

Maintenance refers to all activities carried out to keep equipment, systems, or facilities in proper working condition. This includes routine inspections, repairs, preventive actions, and any corrective measures needed to maintain operational efficiency and safety.
See also: Preventive Maintenance, Corrective Maintenance

Maintainability

Maintainability is a measure of how easily a system or component can be maintained, repaired, or restored to service. High maintainability means that repairs and maintenance tasks can be performed quickly and effectively, thereby minimizing downtime.
See also: MTTR, Reliability

Malcolm Baldrige National Quality Award (MBNQA)

The Malcolm Baldrige National Quality Award is a U.S. award that recognizes organizations for performance excellence. It evaluates companies based on criteria such as leadership, strategic planning, customer focus, measurement and analysis, workforce engagement, and operational effectiveness.
See also: Quality Excellence, Performance Management

Management Review

A management review is a periodic evaluation conducted by an organization’s top leadership to assess the effectiveness of quality, environmental, or other management systems. These reviews help to ensure that the system remains suitable, adequate, and effective for achieving organizational goals.
See also: Continuous Improvement, Strategic Planning

Management Representative

A Management Representative is a designated individual within an organization responsible for overseeing the implementation, maintenance, and continual improvement of a management system (e.g., ISO 9001). This person acts as a liaison between top management and the operational teams.
See also: Quality Management, ISO Standards

Mann-Whitney U Test

The Mann-Whitney U test is a non-parametric statistical test used to determine whether there are significant differences between the distributions of two independent groups. It is often used when the data do not meet the assumptions required for a t-test, especially regarding normality.
See also: Non-Parametric Tests, Statistical Analysis

Mass Production

Mass production is the manufacturing process of producing large volumes of standardized products, often via assembly lines or automated techniques. It focuses on efficiency, reducing cost per unit, and ensuring consistent quality.
See also: Assembly Line Production, Lean Manufacturing

Master Black Belt (MBB)

A Master Black Belt is an expert in Six Sigma methodology who provides strategic leadership, mentorship, and training to teams within an organization. MBBs lead complex improvement projects and are responsible for developing and maintaining the strategic direction of process improvement initiatives.
See also: Six Sigma, Process Improvement

Matrix Diagram

A matrix diagram is a visual tool that displays the relationships between two or more sets of variables in a grid format. It is utilized to analyze, organize, and display data for identification of associations or patterns among factors.
See also: Cause-and-Effect Diagram, Relationship Mapping

Matrix Organization

A matrix organization is an organizational structure where team members have dual reporting relationships – typically both to a functional manager and to a product or project manager. This structure encourages efficient resource use and improved communication across disciplines.
See also: Project Management, Functional Organization

Mean

The mean is the arithmetic average of a set of values, calculated by summing all the values and dividing by the total number of values. It is a primary measure of central tendency used in statistical analysis.
See also: Median, Mode

Mean Time Between Failures (MTBF) – (Repeated)

Refer to the definition for MTBF above.

Mean Time To Failure (MTTF) – (Repeated)

Refer to the definition for MTTF above.

Mean Time To Repair (MTTR) – (Repeated)

Refer to the definition for MTTR above.

Mean Down Time (MDT)

Mean Down Time (MDT) is the average time a system or component remains non-operational due to a failure. MDT encompasses all periods of downtime, including repair, waiting for parts, and verification testing. It is critical for assessing system availability and planning improvements.
See also: MTTR, Uptime Analysis

Measurement System Analysis (MSA)

Measurement System Analysis (MSA) is an evaluation process used to assess the accuracy, precision, and overall capability of measurement systems. One common MSA tool is the Gauge Repeatability and Reproducibility (GR&R) study.
See also: Quality Control, Process Improvement

Median

The median is the middle value of an ordered dataset. Unlike the mean, it is less sensitive to outliers and skewed distributions, making it a robust measure of central tendency.
See also: Mean, Mode

Median Chart

A median chart is a type of control chart that tracks the median value of a process over time instead of the mean. It is particularly useful when data are non-normally distributed or when outliers are present.
See also: Control Charts, Statistical Process Control

Metric

A metric is a quantifiable measure used to track and assess the status of a specific process, activity, or performance objective. Metrics are used for performance evaluation and informed decision making in both business and technical contexts.
See also: KPI, Benchmarking

Mil-Std-105E

Mil-Std-105E is a military standard that outlines sampling procedures and acceptance criteria for quality inspection. It provides guidelines for determining the acceptability of a production lot based on the number of defects found in a sample.
See also: Acceptance Sampling, Quality Control

Mil-Std-414

Mil-Std-414 is a military standard that specifies sampling methods for acceptance testing based on attribute data. It is applied to quality assurance processes in situations where evaluating every item is impractical.
See also: Acceptance Sampling, Attribute Sampling Plans

Milk Run

A milk run is a logistics strategy involving a vehicle making multiple stops to deliver or pick up items from several suppliers or customers in one route. This method optimizes transportation efficiency and reduces waste by fully utilizing the route.
See also: Route Optimization, Supply Chain Management

Minitab

Minitab is a statistical software package designed for data analysis and quality improvement. It offers tools including regression analysis, control charts, design of experiments (DOE), and hypothesis testing, making it popular among Six Sigma and quality professionals.
See also: Statistical Software, Data Analysis

Mission

A mission defines an organization’s fundamental purpose, outlining the primary objectives and the approach the organization takes to achieve them. A clear mission statement guides decision making and communicates the core values of the organization.
See also: Vision Statement, Strategic Planning

Mixture Design

Mixture design is an experimental design approach used when the independent variables are proportions of different components in a blend. It is widely applied in industries such as food, chemicals, and pharmaceuticals to optimize formulations and product performance.
See also: Design of Experiments (DOE), Formulation Studies

Mode

The mode is the value that occurs most frequently in a dataset. It is a measure of central tendency that is especially useful for categorical data or for identifying the most common occurrence within a set of values.
See also: Mean, Median

Moods Median Test

The Moods median test is a non-parametric statistical method used to determine whether the medians of two or more independent groups differ significantly. It is an alternative to more parametric tests when data do not meet the necessary distribution assumptions.
See also: Non-Parametric Tests, Kruskal-Wallis Test

Moving Range Chart (MR Chart)

A moving range chart is a type of control chart used to monitor the variability of a process by plotting the differences between consecutive data points. It is particularly useful for small sample sizes (often individual measurements) to detect process variability.
See also: Control Charts, Process Variability

Muda

Muda is a Japanese term meaning "waste" in lean manufacturing. It encompasses any activity or process that consumes resources without adding value to the final product or service. The elimination of muda is a key objective in lean methodologies.
See also: Lean, Kaizen

Multivariate Control Chart

A multivariate control chart is a tool used to monitor multiple interrelated quality characteristics simultaneously. It takes into account the correlations between variables, offering a comprehensive view of process performance when multiple metrics are critical.
See also: Control Charts, Multivariate Analysis

Multivariate Normal Distribution

The multivariate normal distribution is a generalization of the normal (Gaussian) distribution to multiple variables. It is characterized by a mean vector and a covariance matrix and is fundamental in multivariate statistical analysis and process monitoring.
See also: Multivariate Analysis, Statistical Modeling

Mura

Mura is a Japanese term for "unevenness" or "inconsistency" in a process. It refers to irregularities or fluctuations in operations that can lead to inefficiencies and quality variability. Addressing mura is essential for creating a smooth, predictable workflow.
See also: Lean, Process Optimization

Muri

Muri is a Japanese term meaning "overburden" or the imposition of an unreasonable workload on people or equipment. In lean manufacturing, reducing muri helps prevent errors, stress, and breakdowns, thereby improving overall process efficiency.
See also: Muda, Operational Efficiency