Download EPI Lab 4 - Risky Business

Module Overview
• Risk—what is it?
• How do we perceive risks-socioecological model?
• It’s all relative..
• Where do health statistics come from?
• How can I learn about my risk of having a disease from a given
medical test?
Today’s Overview
• Housekeeping
• Remember, journal entries are due by 4pm on Sunday and comments are due
by the start of class on Tuesday
• Guidelines are posted at: http://riskybusiness.web.unc.edu/assignments/
• Short lecture about reading concepts for the week
• Talk about the video and best practices in reporting numbers
• Group activity: How can we report more responsibly? What is more
risky?
Four Components of Ecological Health
behavior theory
1. There are multiple influences on
specific health behaviors, including
factors at the intrapersonal,
interpersonal, organizational,
community, and public policy levels.
2. Influences on behaviors interact
across these different levels.
3. Ecological models should be
behavior-specific, identifying the
most relevant potential influences
at each level.
4. Multi-level interventions should be
most effective in changing behavior.
How do we report riskrelated numbers?
Kashika Sahay
1/15/2014
Epidemiology
Epidemiology can be defined as the study of the distribution and
determinants of health-related states in specified populations, and
the application of this study to control health problems.
Distribution (Location)
Epidemiologists study the distribution of frequencies and patterns of
health events within groups in a population. To do this, they use
descriptive epidemiology, which characterizes health events in terms
of time, place, and person.
Determinants (Risk factors)
Epidemiologists also attempt to search for causes or factors that are
associated with increased risk or probability of disease. This type of
epidemiology, where we move from questions of "who," "what,"
"where," and "when" and start trying to answer "how" and "why," is
referred to as analytical epidemiology.
Populations (not Individuals)
One of the most important distinguishing characteristics of
epidemiology is that it deals with groups of people rather than with
individual patients.
Count
Simple measure of quantity
Example: The number of stillbirths at Emory
University Hospital in 2009
The number of M and Ms in a bag
Ratio
Obtained by dividing one quantity by another. These quantities may
be related or may be independent.
Example: The number of stillbirths per thousand live births at Emory
University Hospital in 2009
Examples of ratios
Male:Female ratio of students
Odds of winning a bet
Risk of disease for exposed group compared to risk of disease
for unexposed group
A ratio compares the magnitude of one quantity relative to
another
Proportion
A ratio in which the numerator is included in the
denominator
Example: The number of stillbirths out of the total
number of births at UNC Hospital in 2009 (may be
expressed as %)
Proportions, Rates and Ratios have different
properties
• Proportion the numerator is a subset of the denominator
Always between 0 and 1 (or 0% and 100% when expressed as %)
• Rate Number of events per unit of time
Number of events per population where events are counted over a specified
time interval – these rates are similar to proportions
Change rate – not a proportion
• Ratio Not a proportion
Similar quantities from two different groups: the numerator is not a subset of
the denominator
Measures of Disease Frequency
• Incidence (I): Measures new cases of a disease that develop over a
period of time.
• Prevalence (P): Measures existing cases of a disease at a particular
point in time or over a period of time.
RISK
Probability that an event will occur
RATE
A measure of how quickly something happens
Measures of Frequency
• Risk
• Rate
Disease
• Proportion exposed
• Ratio of exposed to non-exposed
Exposure
Comparisons
• Ratio
• Difference
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Relative Risk
• The Relative risk is the ratio of risks for two different populations
• •If the risk of having disease is 2/10 in one population and 1/10 in the
reference population, then the relative risk is:
Activity
• Get into groups of 4-5
• Read through the news article
• Discuss:
• Find a number in the article.
• Discuss if it is responsibly reported.
• Discuss the reasons why it may not be responsibly reported.