Chapter 9: Causality

analogy

A comparison between two things with similarities for the purpose of explanation or clarification

causal inference

A conclusion about the presence of a health-related state or event and reasons for its existence

biological plausibility

a causal association is consistent with existing medical knowledge

coherence

a criterion in a causal inference wherein there is consistency with known epidemiologic patterns of disease

experimental evidence

a criterion in causal inference wherein an experimental study design has the greatest potential for supporting cause-effect relationships because of control over measurements and monitoring, the ability to establish a time sequence of events, and the ability to control for bias by employing an appropriate sample, random assignment, and blinding.

strength of association

a critical criterion in causal inference; a valid statistical association and the stronger the strength of that association provides support for the possibility of there being a causal association

decision tree

a decision tool that uses a graph or model of decisions and their possible consequences

risk factor

a factor that is associated with an increased probability of experiencing a given health problem

chance

a factor to consider when establishing the validity of a statistical association

P value

a function of sample data that helps determine the statistical significance of a result

temporality

a linear process of past, present, and future

confidence interval

a range of reasonable values in which a population parameter lies, based on a random sample from the population

sample

a subset of items that have been selected from the population

hypothesis

a suggested explanation for an observed phenomenon or a reasoned proposal predicting a possible causal association among multiple phenomena

at risk behavior

an activity performed by a person that puts him or her at greater risk of developing a health-related state or event

specificity

an exposure is associated with only one disease or the disease is associated with only one exposure

biologic gradient

an increasing risk of disease occurs with greater exposure

statistical inference

an inference or conclusion made about a population used on sampled data

systematic error

bias that occurs from differences between the truth addressed by the research question and the subjects and measurements in the study

random error

chance variability; the greater the error, the less precise the measurement

enabling factors

factors or conditions that allow or assist the health-related state or event to begin and run its course

Koch's Postulates

four criteria formulated by Robert Koch and Friedrich Loeffler in 1884 and refined and published by Koch in 1890 to establish a causal relationship between a causative microbe and a disease

web of causation

graphic, pictorial, or paradigm representations of complex sets of events or conditions caused by an array of activities connected to a common core or common experience or event

direct causal association

has no intermediate factor and is more easily understood

reinforcing factors

have the ability to support the production and transmission of disease or conditions, or they have the ability to support and improve a population's health status and help control diseases and conditions

indirect causal association

involves one or more intervening factors and is often much more complicated

inductive reasoning

moving from specific observations to broader generalizations and theories

multifactorial etiology

of or arising from many factors

fish bone diagram

provides a visual display of all possible causes that could potentially contribute to the disease, disorder, or condition under study

bias

the deviation of the results from the truth; can explain an observed association between exposure and outcome variables that is not real

precipitating factors

the factors essential for the development of diseases, conditions, injuries, disability, and death

power

the power of a statistical test measures the tests ability to reject the null hypothesis when it is actually false

consistency of association

the relationship between an exposure and outcome variable is replicated by different investigators in different settings with different methods

etiology

the science and study of the causes of disease and their mode of operation

predisposing factors

those existing factors or conditions that produce a susceptibility or disposition in a host to a disease or condition without actually causing it

confounding

to cause to become confused or perplexed

type II error

when H0 is not rejected by H0 is false

type I error

when the null hypothesis (H0) is rejected but the H0 is true