Chapter 5 Flashcards
(39 cards)
What is means by a “causal association?”
A relationship between an exposure factor and disease in the host.
Create an original example of a
Method of Difference
Several, think of this as a discrete (or that there is only a single factor)
A car door is either open or closed
I am either talking or not talking
You are either on your phone or not
What is a confidence interval estimate?
A range of values that with a certain degree of probability contain the population parameter.
Define Association
A degree of statistical relationship existing between two or more disease events or occurrences. Can be positive, negative, or no association.
Amoung Hill’s criteria of causality, what is meant by “biological gradient?”
aka dose-response curve; shows a linear trend in the association between exposure and disease
What is a dose-response curve?
The plot of a dose-response relationship, which is a type of correlative association between an exposure and an effect
What is a contingency table?
A method for demonstrating associations. A type of table that tabulates data according to two dimensions.
Yes No Total
Yes A B A+B
No C D C+D
Total A+C B+D A+B+C+D
What is inference?
The process of passing from observations and axioms to generalizations. A goal of inference is to draw conclusions about a parent population from sample-based data.
Using sugar consumption (exposure variable) and type 2 diabetes (health outcome), list three possible associations between exposure and outcome:
Possible associations between exposure and outcome
- No association (independence) between dietary sugar consumption and occurrence of diabetes
- Positive association between dietary sugar and diabetes
- Noncausal: A third factor may be related to both preference for dietary sugar and occurrence of diabetes.
- Causal: High dietary sugar intake “causes” diabetes.
- Negative association between dietary sugar consumption and diabetes
What is a negative association?
If the value of one variable increases, the value of the other variable decreases.
In statistics, what is power?
The ability of a study to demonstrate an association if one exists.
Create an original example of a
Method of Concomitant Variation
Several, think of this as a continuous (or as the exposure increases, so does the health outcome).
There is a relationship between the amount of alcohol consumed and a decrease in coordination
There is a relationship between the number of miles I run and muscle fatigue
Amoung Hill’s criteria of causality, what is meant by “coherence?”
The cause and effect interpretation of our data should not seriously conflict with the generally known facts of the natural history and biology of the disease.
What is a continuous variable?
A type of variable that can have an infinite number of values within a specified range (example: height and weight).
The stronger the association, the more likely it is that the relationship between events or exposures is due to cause-effect variables.
Therefore, as frequency or intensity of the event or exposure increases, then what happens to the effects and exposure?
The effects from the exposure also increase, the association possibility also increases
What is the method of concomitant variation?
A way of hypothesizing. A type of association in which the frequency of an outcome increases with the frequency of exposure to a factor, the hypothesized cause of the outcome.
(example: dose-response relationship between number of cigarettes smoked and mortality from lung cancer)
Amoung Hill’s criteria of causality, what is meant by “consistency?”
As association has been observed repeatedly.
The _______________ refers to the lowest dose at which a particular response occurs.
Threshold
If Pearson’s r = -0.94 is the association strong or weak?
Strong because
as r approaches either -1 or +1, the association between two variables becomes stronger
What is a positive association?
If the value of one variable increases, the value of the other variable increases as well.
What is operationalization?
Methods used to translate concepts used in research into actual measurements.
Example: In a study of the association between tobacco use and lung disease, the variables might be the number of cigarettes smoked and the occurrence of asthma.
Define variable
Any quantity that varies. Any attribute, phenomenon, or event that can have different values.
Amoung Hill’s criteria of causality, what is meant by “plausibility?”
The association must be biologically plausible from the standpoint of contemporary biological knowledge
Amoung Hill’s criteria of causality, what is meant by “analogy?”
Relates to the correspondence between known associations and one that is being evaluated for causality
