While both terms are used in analysis and problem-solving, a flow chart primarily visualizes a sequence of steps in a process, whereas stratification is a data analysis technique used to separate data into distinct groups to uncover hidden patterns. Although the term "flow chart" can sometimes be used in a specific quality context as a synonym for a "run chart" or related to stratification, their fundamental purposes and applications are quite different.
Understanding Flow Charts (Process Diagrams)
A flow chart, or flowchart, is a diagram that illustrates the steps of a process, system, or computer algorithm. It uses various standardized symbols to represent different types of actions, decisions, or operations, with arrows indicating the direction of flow.
- Purpose: To clearly represent a process, making it easier to understand, analyze, communicate, or improve. They are instrumental in identifying bottlenecks, redundancies, or areas for optimization within a workflow.
- Key Components:
- Ovals (Terminators): Indicate the start or end of a process.
- Rectangles (Process Steps): Represent an action or task.
- Diamonds (Decisions): Show points where a decision is made, leading to different paths.
- Arrows (Connectors): Show the direction of the flow.
- Application: Widely used across various industries for process mapping, program design, troubleshooting, and documenting procedures. For example, a flow chart can map the steps involved in order fulfillment, customer service, or software development.
- Example: A flow chart showing the process for onboarding a new employee, from application submission to first day activities.
- Learn more: Explore the fundamentals of Flowcharts.
Understanding Stratification (Data Analysis Tool)
Stratification is a powerful data analysis technique, considered one of the 7 Basic Tools of Quality. It involves separating a mixed set of data into homogeneous subgroups, or "strata," based on specific characteristics (e.g., machine, operator, time, material, environment). By analyzing these subgroups individually, patterns, trends, or relationships that might be obscured when viewing the data as a whole become evident.
- Purpose: To reveal hidden causes of variation, pinpoint root causes of problems, and identify specific conditions under which defects or issues occur. It allows analysts to "peel back the layers" of data.
- How it Works: Data is collected from various sources or under different conditions. Instead of aggregating all data, it's categorized and analyzed separately for each stratum. For example, defect data might be stratified by shift, machine, operator, or raw material batch.
- Relevance: Stratification, also known as flow or run chart, is one of the 7 Basic Tools of Quality in data analysis. This tool is highly relevant in fields like manufacturing, where business leaders utilize it to identify crucial patterns within multiple data sets and pinpoint root causes of quality issues, leading to targeted improvements.
- Application: Essential for quality improvement, problem-solving, and Six Sigma initiatives. It helps understand "where," "when," and "by whom" problems are occurring.
- Example: Analyzing customer complaint data by stratifying it by product type, region, or customer age group to see if specific patterns emerge.
Key Differences at a Glance
| Feature | Flow Chart (Process Diagram) | Stratification (Data Analysis Tool) |
|---|---|---|
| Purpose | Visualizes and maps a process flow. | Separates data to reveal hidden patterns. |
| Type | Process mapping tool; diagrammatic. | Data analysis technique; statistical. |
| Focus | Steps, sequence, decisions in a process. | Variables, subgroups, data relationships. |
| Output | A visual representation of a process. | Insights into data patterns, root causes. |
| Application | Process documentation, optimization. | Quality improvement, problem-solving. |
Clarifying Terminology: "Flow Chart" in Quality Management
The phrase "Stratification, also known as flow or run chart" from the context of the 7 Basic Tools of Quality can be a source of confusion. It's important to differentiate the general use of a "flow chart" (as a process diagram) from the specialized use of "flow chart" or "flow" in this specific quality context.
When linked to stratification or quality tools, "flow" or "flow chart" often refers to a run chart—a graph that displays observed data in a time sequence. A run chart is typically used after data has been stratified, allowing analysts to visualize trends and patterns within specific subgroups over time. For instance, after stratifying defect rates by machine, a run chart could then plot the defect rates for each individual machine over several weeks to detect trends or anomalies.
While stratification is the technique of separating data, and a run chart is a visual tool for displaying data over time, they are often used in conjunction. Therefore, in some quality management circles, the term "flow" or "flow chart" in this specific context might broadly refer to the act of visualizing data flow or patterns, especially over time, which is a key benefit derived from applying stratification. This specialized terminology should not be confused with the common understanding of a flow chart as a diagram of a process.
In essence, a traditional flow chart shows how a process works, while stratification helps understand why certain outcomes occur by breaking down data into meaningful parts, often visualized with charts like run charts.
