Zero Accidents

The philosophy and supporting practices to make safety first. Zero Accidents means that other aspects of lean management are not credible without a serious workplace-centered and people-centered daily attention to safety.

Zero Breakdowns

The long-term aim in TPM to reduce equipment failures and breakdowns to zero through continuous improvement, predictive, and preventive maintenance.

Zero Defects

A phrase coined by quality guru Philip Crosby which challenged management to commit effort to the goal of doing things right the first time. This was contrary to the conventional wisdom that human error and defects were unavoidable.

Zero Inventory

The philosophy of continuously lowering inventory to expose previously hidden problems in the business. In practice, safety stock, cycle stock, raw materials and inventory for immediate use will be on hand, but these standards are set and continuously challenged.

Zero Quality Control

Using inexpensive mistake-proofing methods to achieve 100% inspection.


A statistical measure that describes a value's relationship to the mean of a group of values.


A statistical test used to determine whether the means of two populations are different when the sample sizes are large and the variances are known. It is assumed to have a normal distribution. A z-statistic, or z-score, represents the number of standard deviations above or below the mean population a score derived from a z-test is. For an accurate z-test to be performed it is necessary to know parameters such as standard deviation.