Healthcare and Medicine Reference
research. The study (data collection, analysis, and interpretation) is planned
to confirm or refute the hypothesis.
Deductive research should lead more often (at least theoretically) to
deductive reasoning in which a conclusion (findings) is definitely true if
premises are true . A study as a deductive argument provides (at least theo-
retically) the absolute support for study findings (conclusions). The study
as a logical argument is deductively valid.
Some aspects of argumentation, reasoning, or scientific method in general
are also considered by many as inference in general: The process of logical
reasoning combines observed phenomena with accepted truths or axioms in
order to formulate generalizable statements. 63 Statistical inference applies such a
process to series of observations and calculates degrees of uncertainty in compar-
isons of various data sets. Causal inference is the thought process and methods
that assess or test whether a relation of cause to effect does or does not exist. 64
In medicine, we infer in two directions:
1. Either from observing individuals individually and applying experience
from these observations to the whole problem that those individuals
represent. “Classical” or field epidemiologists often do so looking at the
characteristics of patients one by one to establish the clinical picture of
disease they represent or studying disease outbreaks or cancer occur-
rence in the community.
2. Or as in clinical medicine, the “clinical epidemiology way,” solving indi-
vidual patients' problems individually by inferring (seeing how they it)
from what we already know about groups of similar patients, medical
care, and the disease they represent.
Figure 2.12 illustrates these two strategies and ways of reasoning. Both
are necessary for good understanding and decision making.
126.96.36.199 Criteria of Causality
The still-evolving criteria of causality in health sciences are largely based on
those of the British philosopher, John Stuart Mill, expanded and adapted for
health sciences much later by Sir Austin Bradford Hill, 65 and applied for exam-
ple to smoking and health by the U.S. Surgeon General's Advisory Committee
on Smoking and Health. 66 Their chronological journey was reviewed by Evans. 67
As Table 2.4 shows, there are multiple criteria of causation to be discussed
and confirmed from one case to another. Most of them are subjects of reflec-
tion, others are subjects of calculation, quantification, and interpretation.