What is attribute data?

Attribute data have a quality characteristic (or attribute) that meets or does not meet product specification. These characteristics can be categorized and counted. Examples of attribute data include sorting and counting the number of blemishes in a particular product (defects), and the number of nonconforming pieces (defectives).

Suppose you want to investigate the quality of a bag of M&Ms. You could rate each candy for different defects such as chips in the candy coating, legibility of the "m" printed on each candy, flat spots or misshaped candies.

Attributes are often evaluated as either pass or fail, or are compared with visual standards with generally up to five different categories. This table shows attribute data you can collect for chips in the coating.
Attribute Attribute is rated as Number of attribute categories
Chip in the coating Pass or fail 2
Number of chips per candy 0, 1, 2, 3, 4 or more chips 5

In the candy example, if you measured the size of the chip defect in the candy coating, the data would be continuous data, not attribute data.