Association of Two variables explained by 3rd variable is?

Association of Two variables explained
by 3rd variable is ?
a) Spurious association
b) Indirect association
c) Direct association
d) Causal association
Correct Answer - B
Ans. is ‘b’ i.e., Indirect association
Descriptive studies help to suggest an aetiological hypothesis.
Analytic and experimental studies test the hypothesis, derived from
descriptive studies and confirm or refute the observed association
between suspected causes and disease.
Association may be defined as the concurrence of two variables
more often than would be expected by chance.
In other words, events are said to be associated when they occur
more frequently togeher than one would expect by chance.
Association can be of following types : -
1 .Spurious association
Observed association between a disease and suspected factor is
spurious, i.e., not real.
In other words there is an observed association when none actually
2.Indirect association
The indirect association is a statistical association between a
variable of interest and a disease due to the presence of another
factor, known or unknown, that is common to both the variable and
the disease.
This third factor (i.e., the common factor) is also known as the
confounding variable.
For example, endemic goitre (disease) is found at high altitudes
(variable), showing thereby an association between altitude and
endemic goitre. But it is due to iodine deficiency which is common at
high altitude. So, iodine deficiency acts as a confounding factor as it
is associated with both high altitude and endemic goitre.
3.Direct (causal) association
a) One to one causal relationship
Two variables are stated to be causally related if change in one is
followed by change in other.
If It does not, then their relationship cannot be causal.
b) Multifactorial causation
The causal thinking is different in non-communicable disease (e.g.,
CHD) where the etiology is multifactorial, i.e., more than one factors
are associated with disease causation