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Anantha Kollengode  |  04/02/2010

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A Simple and Effective Way to Display Data

The check sheet

T

he check sheet is a simple and effective tool useful in lean Six Sigma projects. It is sometimes referred to as a concentration diagram or location plot. It is a handy tool for qualitative and quantitative data gathering and analysis. Check sheets help to systematically collect and organize data and are useful in all phases of the define, measure, analyze, improve, control (DMAIC) statistical and analytical method used in lean Six Sigma.

Check sheet vs. check list

People sometimes confuse a check sheet with a check list. The list we use for groceries and the report you get from the auto repair shop with items checked off after service (oil, filter, tire pressure, tread, etc.) are examples of a check list. The following table highlights some key differences between a check list and a check sheet. 

Check Sheet

Check List

A tally sheet to collect data on frequency of occurrence

A tool used to ensure all important steps or actions have been taken

Custom designed by user

Often a standard form

One of seven quality tools

Not one of the seven quality tools

Example: to document reasons for interruptions in operating room

Example: All items required for a surgery are in the case cart prior to the operation.

When to use the check sheet

Using a check sheet is appropriate when the data can be observed and collected repeatedly by either the same person or in the same location. It is also an effective tool when collecting data regarding frequency and identifying patterns of events, problems, defects, the location of the defect, and defect causes.

Types of check sheets

Commonly used check sheets are tabular check sheets or tally sheets, location check sheets, and graphical or distribution check sheets.

When to use the check sheet

Using a check sheet is appropriate when the data can be observed and collected repeatedly by either the same person or at the same location. It is also an effective tool when collecting data on frequency and identifying patterns of events, problems, defects, and defect location, and for identifying defect causes.

Tabular check sheet or tally sheet

The tally sheet is commonly used to collect data on quality problems and to determine the frequency of events. For example, the tally sheet is useful for understanding the reasons patients are arriving late for appointments, the causes for delays in getting lab results back, etc. It is also useful in determining frequency of occurrence—such as the number of people in line for blood tests at 6 a.m., 6:15 a.m., etc.—in order to understand staffing needs. 

Location or concentration diagram

When you rent a car, you probably receive a document with the sketch of the car which allows you to circle any damages, dents, or scratches on the car with a corresponding mark on the diagram. This is an example of a location diagram sheet as shown in figure 1.

Figure 1: Location diagram sheet

A variation of this could be to mark directly on the form where a mistake occurs. For example, if information is missing on an application, you could mark it directly on the form.

Graphical or distribution check sheet

Using the graphical form, the person collecting the data is able to visualize the distribution of the data. For example, the number of people in line at the registration desk at 15-minute intervals could be counted to determine the staffing needs and the size of the waiting room. See figure 2.

Figure 2: Graphical form

Advantages of using the check sheet

The check sheet is a simple and effective way to display data. It is a good first step in understanding the nature of the problem as it provides a uniform data collection tool. It is very useful to help distinguish opinions from facts in the define and the measure phases of DMAIC.

Some examples

A hospital’s lean Six Sigma team embarked on a project to find reasons for retained foreign objects in patients’ bodies after surgery. The team kept hearing about the frequent interruptions in the operating room, but there was no way to quantify the magnitude of the problem. A check sheet was developed to quantify the interruptions and distractions in the operating room. The team piloted the form for four weeks; the data helped the team to discover that pagers are one of the leading causes of interruptions in the operating room.

The hand-hygiene check sheet piloted by a lean Six Sigma team is another tool that helped to standardize hand-hygiene compliance at the Mayo Clinic. View the hand-hygiene check sheet here.

This article was first published on Six Sigma IQ.  

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About The Author

Anantha Kollengode’s default image

Anantha Kollengode

Anantha (Andy) Kollengode has worked as Quality Improvement Advisor at Mayo Clinic, Rochester, for over two years. Prior to joining Mayo, Kollengode spent 10 years in the food industry in various capacities implementing Quality Assurance, Continuous Improvement, Lean and Six Sigma. Kollengode has his Ph.D. in food science and technology from University of Nebraska and an MBA from Washington University, St. Louis. Kollengode is an ASQ-certified Quality Manager/Operational Excellence, Six Sigma Black Belt and a senior member of ASQ. Kollengode has 10 peer-reviewed publications. In the last year, Kollengode presented at the American College of Surgeons, Institute of Healthcare Improvement (IHI), Mayo Quality Conference and Society for Health Systems conference and Industrial Engineering Research Conference.

Comments

Tukey tally methods

John Tukey came up with some handy methods for tallies. Rather than the four sticks and a fifth diagonal one as is customary in North America, he recommended forming square boxes with a diagonal for the fifth count. As one reviews data quickly for a particular defect, one doesn't have to look at the paper to see where to place the marks as often. The four sides of a square can be drawn and a diagonal can be drawn without lifting the writing instrument from the paper. The other useful technique is the stem and leaf plot. This not only provides the histogram but also a sense of which values predominate in the bins. Tukey's book about Exploratory Data Analysis (EDA) is a worthwhile read.

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