What are the 4 types of quality control?

The four types of quality control (QC) generally refer to the different methods and approaches used to ensure that products or services meet established quality standards. These QC types can vary based on the industry, but they typically include:

1. Process Control

• Description: This type of quality control focuses on monitoring and controlling the manufacturing or development process to ensure that it operates efficiently and produces consistent results.
• Example in Software Development: In software QA, process control might involve setting up code review processes or adhering to development standards that help prevent defects during the development phase.
• Tools: In manufacturing, tools like control charts are used, while in software, tools like static analysis or continuous integration systems (e.g., Jenkins) help monitor the process.

2. Acceptance Sampling

• Description: This involves inspecting a random sample of products from a larger batch to determine if the entire batch meets the specified quality standards. If the sampled items pass, the batch is accepted; if not, it may be rejected or require further inspection.
• Example in Software Development: For software testing, this could mean testing a subset of modules or features in a large system to determine overall software quality.
• Tools: Statistical techniques and tools like random sampling methods are used.

3. Control Charts

• Description: A control chart is a graphical representation used to track a process over time, helping to identify any variations that may indicate defects or issues. It helps differentiate between common cause variations (inherent to the process) and special cause variations (due to external factors).
• Example in Software Development: In Agile or DevOps environments, burndown charts or defect density charts are used to monitor software quality over time and detect if defect rates are deviating from acceptable levels.
• Tools: Control charts, such as X-bar and R charts, are used in manufacturing, while software development might use project management tools like Jira or Azure DevOps.

4. Product Quality Control

• Description: This involves inspecting the final product to ensure it meets the required specifications and standards before delivery. The focus is on detecting defects in the finished product to ensure that only quality products are released to the customer.
• Example in Software Development: In QA, this translates to manual testing, automated testing, and user acceptance testing (UAT), where the finished software is validated to ensure it works as intended.
• Tools: Tools like Selenium (for automation), Postman (for API testing), or JMeter (for performance testing) are used to test the final product in software development.

Conclusion:

The four types of quality control—process control, acceptance sampling, control charts, and product quality control—represent different approaches to ensuring that products or services meet the required quality standards. While these methods originated in manufacturing, many of these concepts have been adapted to software quality assurance (QA), where testing processes, code reviews, and continuous monitoring help ensure high-quality software delivery.