HLTH 444: Exam 1 Study Guide
- Epidemiology: Concerned with the distribution and determinants of
health diseases, morbidity, injuries, disability, and mortality in populations;
epidemiologic studies are applied to the control of health problems in
populations
-Epidemic: The occurrence in a community or region of cases of an illness,
specific health-related behavior, or other health-related events clearly in
excess of normal expectancy
-Pandemic: An epidemic occurring worldwide, or over a very wide area,
crossing international boundaries, and usually affecting a large number of
people
Characteristics of Epidemiology
oPopulation focus
oDistribution
oDeterminants
oOutcome
oQuantification
oControl of health problems
Uses of Epidemiology
oInterdisciplinary approach
oScientific method
oEnhancement of critical thinking ability
oQuantitative and computer methods
oCommunication skills
oInculcation of aesthetic values
Define causal association of non-causal association
oCausal association - relationships between 2 variables
EXAMPLES: scatter plot, correlation coefficients,
contingency tables
oNon-causal association - the disease that may cause the
exposure; and associated with a 3rd
Classify examples of quantitative, qualitative, continuous and
dichotomous data
oQuantitative - characterize the occurrence of disease, morbidity,
and mortality in populations. NUMERICAL VALUES
EXAMPLES: Counts, Incidence, Prevalence
oQualitative - Not Numerical Quantities
EXAMPLES: Maternal status, Sex
Key persons in History of Epidemiology
-Ramazzini: (1633-1714) Is regarded as the founder of the field of
occupational medicine; authored “De Morbis Artificum Diatriba (Diseases of
Workers)” published in 1700
-John Graunt: (1620-1674) First to employ quantitative methods;
known as the Columbus of statistics; published “Natural and Political
Observations Mentioned in a Following Index, and Made Upon the Bills of
Mortality (1662)
-John Snow: (1813-1858) English anesthesiologist who innovated
several of the key epidemiologic methods that remain valid and in use
today; believed cholera was transmitted by contaminated water and was
able to demonstrate this association; Broad St in London
-Robert Koch: (1843-1910) German physician; his postulates
demonstrated the association between a microorganism and a disease
-Hippocrates: (460 BCE-370 BCE) Greek authority who departed from
superstitious reasons for disease outbreaks; suggested disease might be
associated with environmental factors; wrote “On Airs”, “Waters”, and
“Places” in 400 BCE
-Sir Percival Pott: (1714-1788) Is thought to be the first person to
describe an environmental cause of cancer; observed that chimney sweeps
had a high incidence of scrotal cancer
- Distinguish between following curves:
dose-response curve: correlative association between an exposure and
an effect (ex: dose-response relationship between the number of
cigarettes smoked daily and mortality from lung cancer)
oThreshold: lowest dose at which a particular response occurs
multimodal curve: has several peaks in the frequency of a condition
omode: category in a frequency distribution that has the highest
frequency of cases
oPossible reasons for multimodal distributions of health outcomes
include changes in lifestyle and immune status of host and
latency effects
Latency: refers to time period between initial exposure
and a measurable response
epidemic curve: a graphic plotting of the distribution of cases by time
of onset; aids in identifying the cause of a disease outbreak
oEx: Foster Farms Salmonella outbreak
- Understand Pearson Correlation Coefficient in relation to measures of
association with continuous variables
Identify components of generic contingency table
Method for demonstrating associations
Table that tabulates data according to 2 dimensions
oA = exposure is present and disease is present.
oB = exposure is present and disease is absent.
oC = exposure is absent and disease is present.
oD = exposure is absent and disease is
absent.6
666666Know key measures of central tendency such as median, mode, mean,
mid-range
Mean- average of the numbers
oAdd them together then divide by how many numbers are
present in the data
Median- middle of the set
oPut in least to greatest
Mode- Most occurring number
Distinguish between positive and negative associations
-Positive association- relationship between two variables in which
both variables move
Negative association- relationship between two variables in which
an increase in one variable is associated with a decrease in the other.
Define confidence interval, and effect on sample size on confidence
interval
Displays the probability that a parameter will fall between a pair of
values around the mean. Confidence intervals measure the degree of
uncertainty or certainty in a sampling method. They are most often
constructed using confidence levels of 95% or 99%.
Define proportion, percentage, ratio
Proportion- A type of ratio in which the numerator is part of the
denominator. May be expressed as a percentage
Percent- A proportion that has been multiplied by 100.
Ratio- “the value obtained by dividing one quantity by another.”
Define incidence and prevalence:6 Identify case examples of incidence
and prevalence
Incidence- Refers to the occurrence of new disease or mortality
within a defined period of observation in a specified population
oEXAMPLES:6 a week, month, year, or other time period
Prevalence- The number of existing cases of a disease or health
condition, or deaths in a population at some designated time
oEXAMPLE: Point prevalence, Period prevalence, Lifetime
prevalence
Know the relationship between prevalence and incidence
Increase in incidence
Longer duration of the case
In-migration of cases
Prolongation of life of patients without a cure
Define crude death rate, crude birth rate, general fertility rate,
perinatal fertility rate and fetal mortality rate
crude death rate- Can be expressed in terms of any unit size of a
population that is convenient.
crude birth rate- Number of live births during a specified period
such as a year per the resident population during the midpoint of the
year
-general fertility rate- Number of live births reported in an area
during a given time interval divided by number of women age 15–44
years in the area
perinatal fertility rate/ fetal mortality rate- Includes both late
fetal deaths and deaths among newborns. Defined as the number of
late fetal deaths after 28 weeks or more gestation plus infant deaths
within 7 days of birth divided by the number of live births plus the
number of late fetal deaths during a year
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