Pubic Health Terms Flashcards
What is accuracy
Accuracy is the extent to which a measurement reflects the true value
What is precision
Precise” means sharply defined or measured. Data can be very precise, but inaccurate.
- has very little scatter and repeat measurements will give more or less the same value
What can cause high precision but poor accuracy
- a systematic bias has been introduced - using an instrument where the zero position has not been set properly
Why do you use age-specific rates
The application of age-specific rates in a population of interest to a standardized age distribution in order to eliminate differences in observed rates that result from age differences in population composition
What is an agent
A factor, such as a microorganism, chemical substance, or form of radiation, whose presence, excessive presence, or (in deficiency diseases) relative absence is essential for the occurrence of a disease.
What is an age specific rate
- A rate limited to a particular age group
- The numerator is the number of occurrences in that age group; the denominator is the number of persons in that age group in the population.
What is airborne transmission
Airborne transmission refers to situations where droplet nuclei (residue from evaporated droplets) or dust particles containing microorganisms can remain suspended in air for long periods of time
List diseases that are capable of airborne transmission
- Influenza
- Whooping cough
- Pneumonia
- Tuberculosis
- Polio
What is analysis of variance (ANOVA)
- A collection of statistical models and their associated estimation procedures used to analyse the differences among group means in a sample
What is association
Statistical relationship between two or more events, characteristics, or other variables
What is attributable proportion
A measure of the public health impact of a causative factor; proportion of a disease in a group that is exposed to a particular factor which can be attributed to their exposure to that factor
How is attributable proportion calculated
Pe(RR-1) / 1+Pe(RR-1)
What is a bar chart
A graphical technique for presenting discrete data organized sothat each observation can fall into one and only one category of the variable. - Frequencies are listed along one axis and categories of the variable are listed along the other axis.
- The lengths of the bars represent frequencies of each group of observations.
What is bias
Deviation of results or inferences from the truth, or processes leading to such systematic deviation. Any trend in the collection, analysis, interpretation, publication, or review of data that can lead to conclusions that are systematically different from the truth
Give exampels of types of bias
- Selection bias
- detection bias
- information bias
- misclassification
- recall bias
What is a box plot
A visual display that summarizes data using a ‘box and whiskers’ format to show the minimum and maximum values (ends of the whiskers), interquartile range (length of the box), and median (line through the box)
What is a carrier
A person or animal without apparent disease that harbors a specific infectious agent and is capable of transmitting the agent to others
What is a case
In epidemiology, a countable instance in the population or study group of a particular disease, health disorder, or condition under investigation
What is a case control study
A type of observational study. Enrollment into the study is based on presence (case) or absence (
control’) of disease. Characteristics such as previous exposure are then compared between cases and controls
what is case-fatality rate
The proportion of persons with a particular condition (cases) who die from that condition.
- The denominator is the number of incident cases;
- the numerator is the number of cause-specific deaths among those cases.
What is a case report study
A type of descriptive study that consists of a careful, detailed profile of an individual patient.
What is a case series study
A type of descriptive study that describes characteristics of number of patients with a given disease
What is causality
The relating of causes to the effects they produce. Some of the criteria for inferring a causal relationship between an implicated food and illness include: strength of association, consistency of the observed association, temporal sequence of events biological plausibility of the observed association, effect of removing the exposure, dose-response relationships, and the exclusion of alternate explanations (Bradford-Hill criteria).
What measures causality
- Bradford hill criteria
What is the casue of the disease
A factor that is associated with the incidence of the disease so that if the intensity or prevalence of the factor in a population changes, the incidence of the disease changes in ways that cannot be explained by changes in other factors.
What is a cause-specific mortality rate
The mortality rate from a specified cause for a population.
- The numerator is the number of deaths attributed to a specific cause during a specified time interval
- The denominator is the size of the population at the midpoint of the time interval.
What is the chi square test
A test of statistical significance. A Chi Square (X2) test looks at the difference between what we observe in the data and what we would expect if the exposure was not associated with the illness.
What is a clinical trial
A clinical trial is an experiment in which a treatment is administered to humans in order to evaluate its efficacy and safety.
What is a cluster trial
An aggregation of cases of a disease or other health-related condition, particularly cancer and birth defects, which are closely grouped in time and place.
- cluster randomised trial is when rather than individuals being randomized to treatment groups, pre-existing groups are randomized to treatment groups (e.g. schools, villages)
What is a cohort
A well-defined group of people who have had a common experience or exposure, who are then followed up for the incidence of new diseases or events. For example, a group of people born during a particular period or year is called a birth cohort.
What is a cohort study
- A type of observational study that is usually prospective.
- Enrollment into the study is based on exposure characteristics or membership in a group. Disease, death, or other health-related outcomes are then ascertained and compared between groups eg those that are exposed to some factor and those that are not.
What is a common source outbreak
An outbreak that results from a group of persons being exposed to a common noxious influence, such as an infectious agent or toxin. If the group is exposed over a relatively brief period of time, so that all cases occur within one incubation period, then the common source outbreak is further classified as a point source outbreak.
What is a communiable disease
An infectious disease transmitted from an infected person, animal, or reservoir to a susceptible host through an intermediate plant, animal, or the inanimate environment.
What is a confidence interval
A range of values for a variable of interest, e.g., a rate, constructed so that this range has a specified probability of including the true value of the variable. The end points of the confidence interval are called the confidence limits. Usually the 95% confidence interval is reported.
What is a confounding variable
This can occur when an association between a risk factor and disease can be explained by a factor associated with both disease and risk factor.
What is a contingency table
A two-variable table with cross-tabulated data used to calculate a potential association. This is also called a 2X2 table; odds ratios or relative risks are typically calculated from a contingency table:
What is a control
In a case-control study, comparison group of persons without disease.
What is a crossover trial
A randomized trial in which participants are randomized to treatment sequence rather than to one of two or more treatments (as in a parallel group randomized controlled trial). All trial participants receive all treatments, and the response to treatments at the end of each period are compared. Crossover trials are useful for subjective measurements such as pain, or when the effect of treatment is reversible
What is a crude mortality rate
The mortality rate from all causes of death for a population.
What is a cumulative frequency
In a frequency distribution, the number or proportion of cases or events with a particular value or in a particular class interval, plus the total number or proportion of cases or events with smaller values of the variable.
what is a cumulative frequency curve
A plot of the cumulative frequency rather than the actual frequency for each class interval of a variable. This type of graph is useful for identifying medians, quartiles, and other percentiles.
What is a cumulative incidence
A measure of the risk or probability of acquiring disease. The number of new cases of diseases in a specified time period divided by the number of individuals at the beginning of the observation period. Technically, cumulative incidence is not a rate, but a proportion
What is a cross-sectional study
A measure of the risk or probability of acquiring disease. The number of new cases of diseases in a specified time period divided by the number of individuals at the beginning of the observation period. Technically, cumulative incidence is not a rate, but a proportion
What is death to case ratio
The number of deaths attributed to a particular disease
during a specified time period divided by the number of new cases of that disease identified during that same time period
What is demographic information
The ‘person’ characteristics–age, sex, race, and occupation–of descriptive epidemiology used to characterize the populations at risk.
define dependent variable
In a statistical analysis, the outcome variable(s) or the variable(s) whose values are a function of other variable(s) (called independent variable(s) in the relationship under study).
define descriptive epidemiology
The aspect of epidemiology concerned with organizing and summarizing health-related data according to time, place, and person.
define detection bias
This type of bias can occur when persons with a risk factor are more likely to have disease detected because of more intense follow-up
define determinant
Any factor, whether event, characteristic, or other definable entity,
that brings about change in a health condition, or in other defined characteristics.
Define direct transmission
The immediate transfer of an agent from a reservoir to a susceptible host by direct contact or droplet spread.
Describe distribution
In epidemiology, the frequency and pattern of health-related characteristics and events in a population. In statistics, the observed or theoretical frequency of values of a variable.
Describe a dot plot
A visual display of the actual data points of a continuous variable.
Describe droplet spread
The direct transmission of an infectious agent from a reservoir to a susceptible host by spray with relatively large, short-ranged aerosols produced by sneezing, coughing, or talking.
describe an ecological study
A type of study involving the comparison of disease frequency (incidence or prevalence) between populations that are different with respect to one or more risk factors of interest. The risk factor information is not known for individual subjects, but rather as a population characteristic. For example pollution exposure may not be known on an individual level, but is known at a local area district level.
describe effect modification
This refers to variation in the magnitude of a measure of exposure effect across levels of another variable.
describe endemic disease
The constant presence of a disease or infectious agent within a given geographic area or population group
Describe environmental factor
An extrinsic factor (geology, climate, insects, sanitation, health services, etc.) that affects the agent and the opportunity for exposure.
Describe epidemic
The occurrence of more cases of disease than expected in a given area or among a specific group of people over a particular period of time.
Describe the epidemic curve
A histogram that shows the course of a disease outbreak or epidemic by plotting the number of cases by time of onset.
Describe the epidemic peroid
A time period when the number of cases of disease reported is greater than expected.
Describe the epidemiological triad
The traditional model of infectious disease causation. Includes three components: an external agent, a susceptible host, and an environment that brings the host and agent together, so that disease occurs
Describe epidemiology
The study of the incidence, distribution and determinants of diseases in humans, with a view to identifying what causes a particular disease and by doing so discovering ways of preventing the disease
define exposed group
A group whose members have been exposed to a supposed cause of disease or health state of interest, or possess a characteristic that is a determinant of the health outcome of interest.
define excess deaths
How many more deaths have occurred than we would expect, based on historical trends.
define fecal-oral transmission
A type of indirect transmission. Fecal-oral transmission is usually associated with organisms that infect the digestive system. Microorganisms enter the body through ingestion of contaminated food and water.
define frequency distribution
A complete summary of the frequencies of the values or categories of a variable; often displayed in either a histogram, a smoothed distribution curve (assuming an underlying distribution such as a normal [Gaussian] distribution, or a two column table: the left column lists the individual values or categories, the right column indicates the number of observations in each category.
define gravidity
Gravidity is defined as the total number of times a woman has been pregnant. This is distinguished from parity, which is defined as the total number of live births ever had by the woman.
define hazard ratio
The risk of an event (death/disease) at any time point in one group compared to the other. Similar interpretation to a relative risk.
define health
A state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.