Describing disease patterns in populations generally fall into one or more of three categories:
- person (who was affected?)
- place (where did the health event occur?)
- time (when did it occur?)
What does a descriptive epidemiologic study do?
Characterizes the amount and distribution of health and disease within a population.
What are the aims of descriptive studies?
- to evaluate and compare trends in health and disease
- provide a basis for planning, provision, and evaluation of health services
- identify problems to be studied by analytic methods (creation of hypotheses)
What are hypotheses?
Theories tested by gathering facts that lead to their acceptance or rejection.
Name and describe the three types of hypotheses.
Positive declaration (research): there's a positive association. Ex. "Asthma is more common in formula-fed infants compared to breastfed ones."
Negative declaration (null): no difference between groups or no relationship between variables. Ex. "There is no difference in the incidence of asthma between breastfed and formula-fed infants."
Implicit question: starting question.
___ is the assumption you are beginning with and the opposite of what you are testing.
Null hypothesis is the assumption you are beginning with and the opposite of what you are testing.
___ is the claim you are testing.
Alternative hypothesis is the claim you are testing.
What is the alternative hypothesis?
The positive hypothesis/declaration. This says there is an association.
By rejecting the null hypothesis the more ___ the study gets.
power
What does the P value in P>0.5 mean?
placebo
If the P=0.01, then what could infer from it regarding the null hypothesis?
To reject it, the lower the P value compared to 0.05, the greater statistical significance it has, meaning the higher the probability of there being an association.
What is a care report?
Accounts of a single occurrence; gossip.
Ex. I saw a bison in yellowstone national park.
What is a care series?
A grouping of cases that share similar adverse health outcomes. They are often grouped consecutively and list common features. Ex. Reported cases of primary meningoencephalitis (121) between 1937 and 2007
What are cross-sectional studies?
What are the three most variables when looking at person?
- age
- sex
- race/ethnicity
What are the characteristics of time?
- cyclic fluctuations
- point epidemics
- secular time trends
- clustering: temporal, spatial
What does cyclic fluctuations mean?
Periodic changes in the frequency of diseases and health conditions over time. Ex. ^influenza mortality in winte.
What does point epidemics mean?
A group's response to a common source of infection,
What does secular time trends mean?
Gradual changes in the frequency of a disease over long time periods. Ex. Decline of heart disease mortality in the US.
What does clustering mean?
A closely grouped series of events/cases of a disease.