What are 7 Basic QC Tools

7 Basic QC Tools

What are the 7 basic QC tools?

  1. Stratification
  2. Histogram
  3. Check sheet (tally sheet)
  4. Cause and effect diagram (fishbone or Ishikawa diagram)
  5. Pareto chart (80-20 rule)
  6. Scatter diagram
  7. Control chart

Learn about these 7 basic QC tools and start using them quickly.

7 Basic QC Tools

1. Stratification

A technique used to analyze and divide a universe of data into homogeneous groups called -Strata.

Stratification tools is used when the data come from different sources or conditions, such as data collected from different shifts, machines, people, days, suppliers and population groups etc.

Excel Charts - Excel Chart templates
Source: Systems2win

2. Histogram

Histogram allows you to represent frequency distribution of data genuinely and concisely among different corporations of a sample. It allows you to quick and without difficulty identify areas of improvement within your processes. It has a structure much like a bar graph. Each bar inside a histogram represents a group. The peak of the bar represents the frequency of statistics within that group. 

Histograms are in particular helpful when breaking down the frequency of your records into categories inclusive of age, days of the week, bodily measurements, or any other category that can be listed in chronological or numerical order. 

File:Cumulative vs normal histogram

3. Check sheet (or tally sheet)

Check sheet is used for collecting and analyzing data. Data collection is an important activity in the problem solving process as it provides a basis for further action. A data may be numerical, observations and opinion etc. Check sheet is also referred to as tally sheet when quantitative data is captured.

File:Check sheet for motor assembly 7 Basic QC Tools

4. Cause-and-effect diagram (also known as a fishbone or Ishikawa diagram)

Introduced via Kaoru Ishikawa, the fishbone diagram helps users identify the various factors (or reasons) leading to an effect. Named for its resemblance to a fishbone, this excellent management device works through defining a satisfactory-related problem at the right-hand aspect of the diagram, with person root causes and sub causes branching off to its left.   

In fishbone diagram, causes are commonly grouped into six main categories. These categories are measurements, materials, manpower, environment, methods, and machines. These categories let you discover the likely supply of your trouble while keeping your diagram structured and orderly.

File:Cause and effect diagram for defect 7 Basic QC Tools

5. Pareto chart (80-20 rule)

Pareto chart helps to Narrow problem area or prioritize the significant problems for corrective measures. It is primarily based on the 80-20 rule.

It means that 80 percent of the problems/failures are caused by 20 percent of the few major causes/factors which are often referred as Vital Few and the remaining 20 percent of the problems are caused by 80 percent of many minor causes which are referred as Trivial Many. Hence, it gives us information about Vital few from Trivial many.

File:Pareto Chart Example.png - 7 Basic QC Tools

6. Scatter diagram

Scatter diagram is most useful in depicting the connection between two variables. It is good for the professionals trying to identify motive and impact relationships. 

With structured values on the diagram’s Y-axis and unbiased values at the X-axis, every dot represents a common place intersection point. When joined, these dots can highlight the relationship between the 2 variables. The stronger the correlation to your diagram, the stronger the connection between variables.

Scatter diagrams can prove useful as a best control tool whilst used to outline relationships between fine defects. It is viable causes together with environment, activity, personnel, and other variables. Once the relationship among a particular defect and its reason has been established, you can put in force targeted answers with (hopefully) better outcomes.

File:Scatter diagram for quality characteristic XXX.svg ...

 7. Control chart (also called Shewhart chart)

Named after Walter A. Shewhart, this first-class improvement tool can help high-quality warranty experts to decide whether or not or no longer a system is solid and predictable. It makes it easy so that you can become aware of factors that might lead to variations or defects. 

Control charts use a principal line to depict an average or imply along with upper and decrease line to depict top and lower control limits based totally on historical data. You can compare your present day process statistics with historical statistics. You can determine whether your current process is controlled or not.

Using a control chart can save your corporation money and time via predicting technique performance, mainly in terms of what your purchaser or corporation expects in your final product.

File:Rule 2 - Control Charts for Nelson Rules.svg - Wikimedia Commons

In Conclusion, These 7 basic QC tools are very effective in controlling process variations.


Download the below spreadsheets templates and begin entering your own data.

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