if this is approximately 1 (or rather 0.99.), then it displays cumulative probabilities.These can easily be checked by inspecting a number like 2.99: Cumulative from zero The cumulative probability, starting from 0: Prob (0 ≤ Z ≤ 1.57) =.
Complementary cumulative The complement (1–x) of above: Prob(Z ≥ 1.57) =. Tables use at least 3 different conventions, depending on the interpretation of the meaning of an entry such as 1.57: Cumulative This is most common, and gives Prob(Z ≤ 1.57) = 0.9418. 2 Converting from normal to standard normal.Since probability tables cannot be printed for every normal distribution, (there are infinite), it is common practice to convert a normal to a standard normal, and use a Z table to find probabilities. The standard normal distribution, represented by the letter Z, is the normal distribution having a mean of 0 and a standard deviation of 1. Normal distributions are symmetrical, bell-shaped distributions that are useful in describing real-world data. They are used to find the probability that a statistic is observed below, above, or between values on the standard normal distribution, and by extension, any normal distribution. A standard normal table also called the "Unit Normal Table" is a mathematical table for the values of Φ, the cumulative distribution function of the normal distribution.