Module 10 Flashcards
what are the two components of epidemiology?
- descriptive
- analytic
what are the 5 Ws of epidemiology?
- what
- when
- where
- who
- why/how
what is descriptive epidemiology?
- Describes the DISTRIBUTION of health related stated and
events - Describes the FREQUENCY and PATTERN of health-
related states and events - Describes the WHO, WHERE, and WHEN
- Person (who)
- Place (where)
- Time (when)
- Communicates public health problem with the use of tables and graphs
types of trends in time: secular trends
long-term changes in health-related states or events
e.g. development of liver disease can take years on average from alcohol abuse
types of trends in time: short-term trends
brief, often unexpected increases in health-related states or events
e.g. salmonella outbreak
types of trends in time: cyclic trends
periodic increases and decreases in the occurrences of health-related states or events
e.g. influenza infection during flu season
Measures of Disease Occurrence: counts
- Counts
- Number (n)
- Frequency (f)
- Just one number
- Answers the question of ‘how many?’
Measures of Disease Occurrence: ratios
- Compares two things
- Divide the numerator by the denominator
- Expressed as X/Y or X:Y
- Numerator may or may not be part of the denominator
- The numerator and denominator may or may not be
related
ratio: portion
- Numerator is always a part of the denominator
- Calculated as: p = A
A+B - Usually calculated as a decimal e.g., 1/8 =.125
- May be presented as a fraction e.g., 1/8
ratio: percentages
- Numerator is always a part of the denominator
- Just a proportion multiplied by 100 (1/8 =.125 = 12.5%)
ratio: rates
- Frequency of an event in a population in a specified period of time
- Population is always specified
- Time period is always specified
- A rate is a proportion that it represents the number of health-related states or events in a population over a specified period
- Adjusted rates -> very important concept for calculating proportions and rates accurately
what are the four types of descriptive studies?
- Case reports
- Case series
- Cross-sectional surveys
- Ecologic studies
what does a case report involve?
a profile of a single individual
**provide evidence for larger scale studies (hypothesis generating)
what does case series involve?
a small group of patients with a similar diagnosis
**provide evidence for larger scale studies (hypothesis generating)
what is a cross-sectional survey?
- Conducted over a short period of time (usually a few
days or weeks) and the unit of analysis is the individual - There is no follow-up period
- Also called prevalence survey
