Types of Data

Actionable Information from Soft Data

Engineers, Six Sigma practitioners and other researchers often work with “hard” data – discrete data that can be counted and legitimately expressed as ratios. But what of “soft” data, things like opinions, attitudes and satisfaction? Can statistical process controls (SPC) be applied here? Can process variation in customer satisfaction, for example, be measured and then reported to…


Attribute Data: Making the Most of What’’s Available

Six Sigma practitioners are aware of the range of numeric data types, from attribute data counts and tallies to continuous data measures on a scale. As the information strength in an element of data depends on the number of potential values it might take on, attribute yes/no data has to be considered the weakest. Many…

Analytical Treatment of Discrete Ordered Category Data

Ordered category data is discrete data representing appraiser or client perception against a rating scale such as a survey or questionnaire. Black Belts learning to apply the Six Sigma methodology to ordered category data are traditionally taught analytical methods that include normal and Poisson distributions. This is probably due to Six Sigma’s beginnings in manufacturing….