HOSA Epidemiology Exam
Bias A flaw in either the study, design, or data analysis that leads to an erroneous
result.
Case Fatality Rate (CFR) A mathematical quantity that describes the severity of a disease; usually applied
to acute diseases. It is the proportion of persons diagnosed with a disease who
actually die from the disease during the period of observation; high CFRs are
considered more severe than low CFRs.
CFR Formula # dying from disease Y in population P
-----------------------------------------------------------
# with disease Y in population P
Comparison of Rates A measure of incidence or occurrence of a disease in a population.
Rate Difference Formula (rate of disease Y among those exposed to X) - (rate of disease Y among those
NOT exposed to X)
Relative Risk / Rate Ratio (RR) Formula Rate of Y among those exposed to X
----------------------------------------------------------
Rate of Y among those NOT exposed to X
Incidence Formula # develop disease Y in pop. P in time T
--------------------------------------------------------------------
# in pop. P
Precision Refers to the degree to which there is variation in a measurement.
Accuracy Refers to the degree to which the measurement is, on average, correct.
Population Controls Serve as the references against which cases are compared; Population controls
drawn from general population contrasted with controls drawn from specific
subgroups (hospital controls, family controls,etc)
Mortality Refers to death; death rates.
Morbidity used to refer to illness; rates of illness.
Exposure Generic term for the effective presence of any agent or factor that is thought to
cause a disease.
Ex: toxic chemical, dietary habits, activity levels, microorganisms.
Endemic Baseline incidence rate in a pop; at ay point in time, people are acquiring a given
disease in the pop.
Ex: flu rate
Epidemic A greater incidence of the disease in a pop. than would normally have been
expected; greater than endemic or baseline incidence.
Disease Transmission Describes the process of the spreading of a disease through a population;
Investigators ask "Who got it & how did it spread?"
, HOSA Epidemiology Exam
Contingency Table Often used to show the relationship between disease and exposure; used to
divide persons into the categories of diseased & exposed (A), diseased & NOT
exposed (B), NOT diseased & exposed (C), NOT disease & NOT exposed (D).
Contingency Table Example --------------------------------Exposure-------
----------------------------YES ----------NO-----
--------------------YES---a---------------b----
Disease-----------NO----c--------------d------
Confounding the complication of analysis due to the presence of a third factor that is
associated with both the putative risk factor and the outcome
Conditional Probability The probability of an event given the occurrence of another event; the probability
of disease (Y) given exposure to factor (X).
Prevalence A mathematical quantity that describes the presence of a disease (Y) in a
population (P); proportion of persons in the population (P) with disease (Y).
Prevalence Formula # with Y in P
---------------------
# in P
Incidence A mathematical quantity that describes the occurrence of a disease (Y) in a
population (P); proportion of persons in the pop. (P) who newly develop the
disease (Y) within a given time period (t).
Racial & Ethnic Health Disparities Used to describe differences in disease rates by rates or ethnicity.
Ex: sickle cell anemia in African Americans
Relative Risk aka (MA): Common Measures of Association; any mathematical measure that is
used to quantify the association between two or more variables.
Attributable Risk (AR) a group of measures which describe the amount of disease risk that can be
attributed to a given factor (X).
Ex: Attributable Fraction
Attributable Fraction (AF) the proportion of disease (Y) in the population (P) that can be attributed to factor
(X).
AF Formula [(incidence in P)-(incidence in unexposed)]
----------------------------------------------------------
(incidence in P)
Screening the process of early diagnosis of a disease; identification of disease or risk
factors for the disease in its pre-symptomatic or pre-clinical stage.
Ex: cervical cancer screening.
Decision making about risk A probability of developing disease given a set of circumstances. We are often
concerned about how well people know the risks associated with various factors
(behaviors, agents, etc) and how clearly they judge the harm or benefit
associated with a given outcome - as well as the extent to which they use that
knowledge when making their health-related decisions.
Ethic Epidemiologists must consider the fair and just treatment of their study subjects,
as well as accuracy and honesty in statistical analysis, interpretation and
dissemination of study data.
Bias A flaw in either the study, design, or data analysis that leads to an erroneous
result.
Case Fatality Rate (CFR) A mathematical quantity that describes the severity of a disease; usually applied
to acute diseases. It is the proportion of persons diagnosed with a disease who
actually die from the disease during the period of observation; high CFRs are
considered more severe than low CFRs.
CFR Formula # dying from disease Y in population P
-----------------------------------------------------------
# with disease Y in population P
Comparison of Rates A measure of incidence or occurrence of a disease in a population.
Rate Difference Formula (rate of disease Y among those exposed to X) - (rate of disease Y among those
NOT exposed to X)
Relative Risk / Rate Ratio (RR) Formula Rate of Y among those exposed to X
----------------------------------------------------------
Rate of Y among those NOT exposed to X
Incidence Formula # develop disease Y in pop. P in time T
--------------------------------------------------------------------
# in pop. P
Precision Refers to the degree to which there is variation in a measurement.
Accuracy Refers to the degree to which the measurement is, on average, correct.
Population Controls Serve as the references against which cases are compared; Population controls
drawn from general population contrasted with controls drawn from specific
subgroups (hospital controls, family controls,etc)
Mortality Refers to death; death rates.
Morbidity used to refer to illness; rates of illness.
Exposure Generic term for the effective presence of any agent or factor that is thought to
cause a disease.
Ex: toxic chemical, dietary habits, activity levels, microorganisms.
Endemic Baseline incidence rate in a pop; at ay point in time, people are acquiring a given
disease in the pop.
Ex: flu rate
Epidemic A greater incidence of the disease in a pop. than would normally have been
expected; greater than endemic or baseline incidence.
Disease Transmission Describes the process of the spreading of a disease through a population;
Investigators ask "Who got it & how did it spread?"
, HOSA Epidemiology Exam
Contingency Table Often used to show the relationship between disease and exposure; used to
divide persons into the categories of diseased & exposed (A), diseased & NOT
exposed (B), NOT diseased & exposed (C), NOT disease & NOT exposed (D).
Contingency Table Example --------------------------------Exposure-------
----------------------------YES ----------NO-----
--------------------YES---a---------------b----
Disease-----------NO----c--------------d------
Confounding the complication of analysis due to the presence of a third factor that is
associated with both the putative risk factor and the outcome
Conditional Probability The probability of an event given the occurrence of another event; the probability
of disease (Y) given exposure to factor (X).
Prevalence A mathematical quantity that describes the presence of a disease (Y) in a
population (P); proportion of persons in the population (P) with disease (Y).
Prevalence Formula # with Y in P
---------------------
# in P
Incidence A mathematical quantity that describes the occurrence of a disease (Y) in a
population (P); proportion of persons in the pop. (P) who newly develop the
disease (Y) within a given time period (t).
Racial & Ethnic Health Disparities Used to describe differences in disease rates by rates or ethnicity.
Ex: sickle cell anemia in African Americans
Relative Risk aka (MA): Common Measures of Association; any mathematical measure that is
used to quantify the association between two or more variables.
Attributable Risk (AR) a group of measures which describe the amount of disease risk that can be
attributed to a given factor (X).
Ex: Attributable Fraction
Attributable Fraction (AF) the proportion of disease (Y) in the population (P) that can be attributed to factor
(X).
AF Formula [(incidence in P)-(incidence in unexposed)]
----------------------------------------------------------
(incidence in P)
Screening the process of early diagnosis of a disease; identification of disease or risk
factors for the disease in its pre-symptomatic or pre-clinical stage.
Ex: cervical cancer screening.
Decision making about risk A probability of developing disease given a set of circumstances. We are often
concerned about how well people know the risks associated with various factors
(behaviors, agents, etc) and how clearly they judge the harm or benefit
associated with a given outcome - as well as the extent to which they use that
knowledge when making their health-related decisions.
Ethic Epidemiologists must consider the fair and just treatment of their study subjects,
as well as accuracy and honesty in statistical analysis, interpretation and
dissemination of study data.
