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TABLE 2.4 Effect of Global Warming
The Facts
President's Decision on Emissions
Reduce emissions
Gather more data
Change
unnecessary
No effect
Economy disrupted
Sampling cost
Burning of
Sampling cost
Decline in quality
fossil fuels
Decline in quality of
of life
responsible
life (irreversible?)
(irreversible?)
then, just as is done today, make one of three possible decisions: reduce
emissions, leave emission standards alone, or sit on our hands and wait for
more data to come in. Each decision has consequences as shown in
Table 2.4.
As noted at the beginning of this chapter, it's essential that we specify in
advance the actions to be taken for each potential result. Always suspect
are after-the-fact rationales that enable us to persist in a pattern of conduct
despite evidence to the contrary. If no possible outcome of a study will be
sufficient to change our mind, then perhaps we ought not undertake such
a study in the first place.
Every research study involves multiple issues. Not only might we want
to know whether a measurable, biologically (or medically, physically, or
sociologically) significant effect takes place, but also what the size of the
effect is and the extent to which the effect varies from instance to
instance. We would also want to know what factors, if any, will modify the
size of the effect or its duration.
We may not be able to address all these issues with a single data set. A
preliminary experiment might tell us something about the possible exis-
tence of an effect, along with rough estimates of its size and variability. It
is hoped that we will glean enough information to come up with doses,
environmental conditions, and sample sizes to apply in collecting and eval-
uating the next data set. A list of possible decisions after the initial experi-
ment includes “abandon this line of research,” “modify the environment
and gather more data,” and “perform a large, tightly controlled, expensive
set of trials.” Associated with each decision is a set of potential gains and
losses. Common sense dictates that we construct a table similar to Table
2.2 or 2.3 before we launch a study.
For example, in clinical trials of a drug we might begin with some
animal experiments, then progress to Phase I clinical trials in which, with
the emphasis on safety, we look for the maximum tolerable dose. Phase I
trials generally involve only a small number of subjects and a one-time or
short-term intervention. An extended period of several months may be
used for follow-up purposes. If no adverse effects are observed, we might
decide to go ahead with a further or Phase II set of trials in the clinic in
