In this chapter, we’re going to cover the check sheet, also known as a tally sheet. This is the data collection form that we create in order to capture data about our processes. We use check sheets to capture data very quickly, such as defects found in a manufacturing organization. Or the frequency that a particular problem occurs in a process. A properly designed check sheet should be very easy to use, and requires no experience, and very little training to begin gathering data. This is a good technique for performing a simple analysis very quickly to identify what might be going wrong in processes.
In a basic check sheet, we start with a simple matrix form where we list the defects on the first column on the left. Let’s say that in a manufacturing process there are a number of defects that could occur with our deliverables. They can be chipped, dented, scratched, or have missing parts. We may place a check sheet on the manufacturing floor and ask the operator that each time we have a defect to make a little tick mark in the appropriate box. The operator would simply tick the boxes for each of the defects they found during the week. Pretty quickly, we’d be able to see at a glance how many total defects we had for the week and which of these tended to be the issue. We may also accumulate the data over a longer period of time, say, over a four week period. This will give a more comprehensive view of which of these are the main issues and how often they’re actually happening. Traveler check sheets are a very powerful method where we attach the check sheet to a particular order, or unit of work, going through the system. And at each step in the process, we asked the operators to capture how many defects they found. For example, during the first step in the process, we would note how many defects we found. And during the next step of the process, how many defects we found, and so on. After multiple units have gone through the system, you begin to get an idea about which steps in the process tend to have the most issues.
This is another powerful tool called the location check sheet. We can make an image of the item that we are assessing. For instance, in a chemical production process, we may illustrate a nozzle going through a combustion chamber, where it is increasing the energy of the gas in order to create pressure and thrust. Valves then allow the fuel to move through the pumps and into a fuel tank. This is also called a measles chart, because we ask the operators to make little red marks on the chart where they’re finding the problems. During the time period that we are capturing the data, we have an instantaneous view of where the problems are. For example, perhaps we identified many issues associated with the combustion chamber. Because that’s the way it’s designed, we can differentiate between which of the two valves is giving us trouble. Or which of the two pumps may be giving us trouble. The location check sheet is very powerful and very visual. It allows us to zero in on where we need to focus our efforts first.
The next type of check sheet is called a confirmation check sheet. This is a simple method to understand what steps must be performed and in what sequence. For example, in a manufacturing process, we may follow steps in this specific order. Create mixture, switch on the granulator, verify the air temperature is 64 degrees, spray it with solvent, air dry, and inspect for defects. We follow the steps in the correct order for consistency and to get it right the first time. This could also be used for things like troubleshooting technical issues for a customer on an inbound call. Or completing an order entry to make sure that we don’t miss any steps and that we ask all the right questions.
Let’s recap the elements of effective check sheets. First, keep it simple. If it’s too complex to complete the check sheet, it won’t get done. All fields on the check sheet must be marked clearly so that anyone entering the data will know what to do and when to do it. Include space to capture date and time, and the collector’s name. Then, identify the criteria for stratifying the data. For instance, if there are three different things that could go wrong at a particular step in the process, we probably want to list each one. Or provide easy to use codes to quickly and easily fill in the check sheet. Even if we feel confident that we have designed a good check sheet, it’s a good idea to run a pilot test with process users. We should ask them for feedback on how we can improve the check sheet so that it will be an effective tool for capturing data about our process.