Within the Six Sigma Methodology, the goal is to develop a flawless process for manufacturing a product or delivering a service. The statistical review can be used for any business function and collects data to determine how to best achieve perfection in the operation.

Conclusions that are made are based on the data which is collected, so the results will only be as good as the information that is obtained. A sound collection plan is imperative to protect the integrity of the Six Sigma process.  Data must be collected in a sound and efficient manor for the success of the entire project.

There are two basic types of data that are gathered, qualitative and quantitative. Quantitative data is numerical and qualitative is not. Qualitative data will typically come from interviews or customer surveys and it is this type that can give you your most important information. Collecting interactional data can be done in a variety of ways from face to face meetings, to questionnaires sent to customers and suppliers.

When you interact with the key people involved in the process, you have a better idea of what their needs are and how to meet them. The Black Belt in Six Sigma who leads a quality review will try and turn the qualitative data into information that is quantifiable.   Their answers are then usually ranked in order to perform numerous statistical tests.  The interactional data will be transposed into a numerical form that can be charted and analyzed for clues on where there might be flaws in the system. While this type can be subjective, the Six Sigma team will work to remove any bias. A great deal of time will be spent developing the questions that will be asked in the interviews and determining who will be questioned.

When gathering interactional data from employees or customers, you always have to be on the alert for any bias that they may have creeping into their answers. Does the employee have an ax to grind against someone in management?, or did the customer have a bad experience with a sales person? While the answers could reflect a problem in the company, they could also just reflect a personality clash. This is why it is so important to try and gather only sound data that will help support the review. Some responses may have to be thrown out if they are that much in conflict with the remarks from others who are responsible for the same functions, and are called outliers. What the Six Sigma team has after is honest input, and they have to do a good job of making sure that the people they are dealing with are being truthful.