STATISTICAL TOPICS AND ANALYSIS IN RISK ASSESSMENT - Risk Management Applications in Pharmaceutical and Biopharmaceutical Manufacturing - page 73

attempt to provide a complete understanding of the topic, as that content would
need its own library wing. It does, however, attempt to provide a brief overview
of points to consider and ponder when you attempt to quantify the probability
dimension of risk.
4.2 UNCERTAINTY
John Maynard Keynes declared there are times and places were no “probability
calculus” would be possible. He called this true uncertainty [1]. Keynes argued
that uncertainty could not be defined objectively as there may be no knowledge
of a hazard. Others say risk and uncertainty are and the same and attempt to
quantify the subjective portion of risk. This is an attempt to create an enumerative
vehicle for a subjective expected utility. There is a difference between what is
possible, merely probable, uncertain, and true uncertainty. Something is simply
uncertain when we have yet to collect data; think of process development here.
True uncertainty lies in areas where it is impossible to measure, such as the
probability of war between China and the United States, or the obsolescence of
an invention such as a microwave oven or an iPad. We simply do not know.
As Keynes put it, even “the weather is only moderately uncertain”; a statement
made well before the weather technology of today [2].
In practice, risk is on a sliding scale. In some cases, it can be defined in
objective terms, in others it is subjective. In applications of risk assessment
where uncertainty exists, people try to assess uncertainty within a subjective
rating instead of simply stating “I don't know” and collecting data. ∗
By combining definitions from several sources, uncertainty is defined here as
an unquantitated lack of specific knowledge. “Looks like rain,” is uncertainty
statement.
By comparison, a quantitated lack of specific knowledge is the basis for the
complementary fields of probability, statistics, and risk. “A fifty percent chance
of rain” is a probability statement.
4.3 LUCK AND PROBABILITY
Luck is probability taken personally.
—Anonymous
The duality of this statement illustrates the nature of probability in our soci-
ety. Millions of people believe in luck but not in probability. A short example
illustrates the point. If we flip a quarter six times and get heads each time, most
people on the street or in a casino believe that the probability of getting a tail on
the seventh flip is greater than if we had gotten three heads and three tails. They
would in fact literally bet money on it.
∗ For an expanded discussion, read Nassim Nicholas Taleb's The Black Swan.