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Section 5.6 Standard Units

Definition 5.6.1. Conversion to Standard Units.

Any distribution variable can be converted to “standard units” using the linear translation
z=xμσ.
In doing so, values of z will always represent the number of standard deviations x is from the mean and will provide “dimensionless” comparisons.
Consider our earlier continuous example 5.4.4 in which we found μ=54 and σ=5180. Then,
P(0<X<1)=P(0545180<X545180<1545180)
gives the middle term is Z and the other endpoints are now in standard units that indicate the number of standard deviations from the mean rather than actual problem units.