Sample size and evolution:
Large industrial processes usually possess only one or two
assets of any one type. They tend to be brought into opera-
tion in series rather than simultaneously. This means that
sample sizes tend to be too small for statistical procedures
to carry much conviction. For new assets with high levels
of leading-edge technology they are always too small.
These assets are also in a continuous state of evolution
and modification, partly in response to new operational
requirements and partly in an attempt to eliminate failures