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Association and Casuality ( CH 5)

Terms in this set (28)

What does the term Association mean?
Association refers to a linkage between one or among variables. These variables are associated with one another either positively or negatively.
What is a positive association?
A positive association is as one of the variable increases so does the value of the other variable.
What is a negative association?
A negative association is as the value of one variable increases, the value of the other variable decreases.
What is a Continuous Variable ?
A continuous variable is a type of variable that can have an infinite number of values within a specified range.

Example: Weight & Height
What is Dose-Response Curve?
A Dose response curve is a plot of dose-response relationship that a type of correlative association between exposure (dose of toxic chemical) and effect (biologic outcome).

Indicator to assess a casual effect of suspected exposure association with adverse health outcomes.
What is a threshold in Dose Response curve?
Threshold refers to the lowest dose at which a particular response occurs. Note: when the maximal response is reached, the curve flattens out.
What is a Multimodal Curve ?
A multimodal curve is one of that has several peaks in the frequency of a condition.

Multimodal distribution changes in the immune status or lifestyle of the host.
What is a Mode?
A mode is defined as the category in a frequency distributed that has the highest frequency of cases.
What is Latency?
Latency refers to the time period between initial exposure and a measurable response.
What is a Epidemic Curve ?
A epidemic curve is graphic plotting of the distribution of cases by time of onset.

A type of unimodal curve aids in identifying the cause of a disease outbreak.
What is a Contingency table ?
A contingency table which is a type that tabulates data according to two dimensions.
What is a casual association?
A casual association exist between an exposure factor and disease in the host.
Criteria of Casuality
The determination of casual relationships between exposures and outcomes remains a difficult issue for epidemiology which relies primarily on observational studies.

The entire criteria must be evaluated , no one criteria can determine causality
What is a noncasual association?
A noncasual association could be merely a one time observation, due to chance and random factors or due to errors in the methods procedures.
Strength
Strong association give support to a causal relationship between factor and disease.

Ex: The large increase of scrotal cancer among chimney sweep workers in comparison to non workers
Consistency
Consistent association must be observed " by different persons, in different places, circumstances and times"

Ex: association between smoking and lung cancer found in retrospective and prospective studies.
Specificity
A specific association is one that is constrained to a particular disease exposure relationship.

Given disease results from a given exposure and not from other types of of exposures
Temporality
You must observe the cause before the effect

EX: air pollution causes cancer
follow people who are exposed to air pollution and observe whether they get cancer or not
Biological Gradient
Dose-Response Curve which shows a linear trend in association and exposure.
Plausibility
The association must be biologically plausible from the standpoint of contemporary biological knowledge.

*It make sense biologically

Ex: Scrotal cancer & Chimney Sweeps
It is plausible in view of current knowledge about carcinogenesis.
Coherence
" Cause an Effect interpretation of our data should not serious conflict the generally known fats of the natural history and biology of disease"

Ex: Cigarette smoking and lung cancer come from the rise in # of deaths associated by increased smoking as well as cancer mortality difference between men & women (Men die more).
Analogy
The correspondence between known associations and one that is being evaluated for casuality.
A study that compares individual who have a disease with individuals who do not have the disease in order to examine the differences in exposures or the risk factors for the disease.
Case Control Study
Time period between initial exposure to an agent and development of measurable response.
Latency
The latency period can range from seconds to decades.
A computed interval of values that with a given probability is said to contain the true value of the population parameter.
Confidence Interval
The assertion that the observed association is not likely to have occurred as a result of chance.
Statistical Significance
A portrayal of causality wherein several individuals, community and environmental factors interact to cause a particular disease.
Multiple Causality
Methods used to translate concepts used in research into actual measurements.
Operationalization
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