Check Sheets and Types – 7 QC Tools

What is a Check Sheet?

A check sheet is a simple counting tool. It serves as a data-collecting tool used for gathering and visualizing the parameters which are under study. The check sheet is used for almost every industry and process. The check sheet is identified as one of the basic 7 QC Tools. Due to its simplicity, the check sheet is primarily used by the operators or the people who are involved in the work. By collecting data on a check sheet, common patterns and trends can also be identified.

History of Check Sheet

Check sheet concept is nothing new to us. It is derived from the famous tally marking concept used by ancient people. Between 35,000 and 25,000 years ago, in the form of notched bones, tally counting is found to be done in Africa’s Late Stone Age.

Sometimes, a tally marking system was used for numbering also. A technique that has been the sole basis for the shepherds to count their cattle before and after they went for grazing was this tally marking and sometimes stones were used for that.

The counting system had been evolving since then.

Applications of Check Sheet

In Six Sigma, the Measure phase of the DMAIC approach consists of several tools including the check sheet. Sometimes the data collected from the check sheet is used as primary data to understand the problem before initiating the analysis.

In general, the check sheet is used for collecting qualitative data (colors, defect types, names, etc.) and quantitative data (temperature, dimension, weight, etc.). Fig.1- shows an example of a check sheet used for capturing paint nonconformities and Fig. 2- shows an example of temperature measurement.

Figure -1 – Check sheet for paint defects

In Fig2, the scale on the bottom represents the boundaries for each dimension range. Sometimes, instead of writing the actual value, some markings are done as indicated in the figure below.

igure-2- Check sheet for dimensions

The typical types and its uses of check sheets as a part of 7 QC tools are given below,

  1. Process distribution check sheet – to understand the distribution and mean of the collected data visually
  2. Defective item check sheet – to understand the no. of defectives in a group or sample
  3. Defective location check sheet – to identify which location of a product has more defects and the types of defects
  4. Defective cause check sheet – to count the maximum no. of causes of a defect

How to Draw a Check Sheet

  1. There are no hard and fast rules in designing the check sheets as it is the user’s discretion to use his creativity for better capturing and understanding purpose.
  2. You must ensure that it should be user-friendly and, wherever possible, include information on time and location.
  3. You should know the type of data you are going to collect and accordingly the check sheet to be designed. Some of the widely used check sheet designs are given below for reference.
  4. Also, decide who will collect the date and what time period and how the data will be collected.
  5. You can modify the check sheet form for each situation as required by the operation team.
  6. Continuously review the check sheet information to redesign for better visualization of contents.
  7. The captured data is used for further analysis. If required a secondary check sheet is prepared for collecting based on the output of the analysis.

References:

  1. https://en.wikipedia.org/wiki/Tally_marks
  2. https://sites.google.com/site/largenumbers/home/1-2/tallies

By Surender Gowthaman

Blogger, Theory of Constraints-Lean-Six Sigma Practitioner, Lead Auditor in QHS

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