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