A value, usually of a test statistic (seehypothesis test), that is hypothesized to have come from a normal distribution with mean 0 and variance 1. The z-notation was introduced by Sir Ronald Fisher in 1924.
Chemical Engineering
The temperature rise required in degrees Celsius that is able to bring about a ten-fold decrease in the thermal death time of microorganisms. It is used in the thermal sterilization process of foods that may be contaminated with harmful microorganisms. The thermal death time is the time required to reduce the number of surviving microorganisms to an acceptable level. A typical value for the thermal destruction of vegetative microorganisms is around 10ºC.