Page 251 - Six Sigma Demystified

Part 3 s i x s i g m a to o l s 231

Normal Distributions

Minitab

Use Calc\Random Data\Normal to generate random numbers.

Use Stat\Quality Tools\Individual Distribution Identification to test whether the
sample data meet the normal distribution. Use goodness-of-fit tests (described
below) to determine if an assumed distribution provides a reasonable
approximation.

Excel

Use Data\Data Analysis\Random Number Generation.
Set Distribution = Normal.

Lognormal Distribution
Used for measurement (continuous) data that theoretically are without bound
in only the positive direction and bounded at zero (or a positive value above
zero), the lognormal distribution is often applied to reliability and financial
analysis. Data that are normally distributed, when transformed using the natu-
ral log function, will follow the lognormal distribution.

Lognormal Distributions

Minitab

Use Calc\Random Data\LogNormal to generate random numbers. Specify loca-
tion, scale, and threshold.
Use Stat\Quality Tools\Individual Distribution Identification to test whether the
sample data meet the lognormal distribution. Use goodness-of-fit tests
(described below) to determine if an assumed distribution provides a reason-
able approximation.
(Continued)