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What type of variable is a county of residence in epidemiology?
What type of variable is a county of residence in epidemiology?
What is the definition of health according to the World Health Organization (WHO) in 1948?
What is the definition of health according to the World Health Organization (WHO) in 1948?
What is the term for the progression of a disease process in an individual over time, in the absence of treatment?
What is the term for the progression of a disease process in an individual over time, in the absence of treatment?
What is the main difference between a ratio and a proportion in epidemiology?
What is the main difference between a ratio and a proportion in epidemiology?
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What is the term for the condition of being diseased?
What is the term for the condition of being diseased?
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What is the main characteristic of nominal-scale variables in epidemiology?
What is the main characteristic of nominal-scale variables in epidemiology?
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What is the primary characteristic of a ratio-scale variable?
What is the primary characteristic of a ratio-scale variable?
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What is the purpose of the numerator in a frequency measure?
What is the purpose of the numerator in a frequency measure?
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What is the distinguishing feature of a nominal variable with two categories?
What is the distinguishing feature of a nominal variable with two categories?
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What is the term for the relative magnitude of two quantities or a comparison of any two values?
What is the term for the relative magnitude of two quantities or a comparison of any two values?
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What is the characteristic of an interval-scale variable that distinguishes it from a ratio-scale variable?
What is the characteristic of an interval-scale variable that distinguishes it from a ratio-scale variable?
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What is the term for the spread of a distribution, as revealed by a graph?
What is the term for the spread of a distribution, as revealed by a graph?
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What is the secondary attack rate among family contacts of cases?
What is the secondary attack rate among family contacts of cases?
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What is the relation between prevalence and incidence in a steady-state?
What is the relation between prevalence and incidence in a steady-state?
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What is the main purpose of measuring prevalence in a community?
What is the main purpose of measuring prevalence in a community?
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Why is it crucial to have correct interpretations in epidemiology?
Why is it crucial to have correct interpretations in epidemiology?
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How many decimal places should final answers have in epidemiological calculations?
How many decimal places should final answers have in epidemiological calculations?
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What is the percentage of people who became ill with diarrhea among those who ate cantaloupe at the Lansing picnic?
What is the percentage of people who became ill with diarrhea among those who ate cantaloupe at the Lansing picnic?
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What is the term for the person who gets the disease from eating contaminated food, for example, egg salad?
What is the term for the person who gets the disease from eating contaminated food, for example, egg salad?
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What is the formula for calculating the primary attack rate?
What is the formula for calculating the primary attack rate?
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In the example of the hepatitis A outbreak, what is the total number of persons in the 7 affected families?
In the example of the hepatitis A outbreak, what is the total number of persons in the 7 affected families?
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What is the term for the percentage of people who become ill among those who were exposed to a primary case?
What is the term for the percentage of people who become ill among those who were exposed to a primary case?
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What is the percentage of people who became ill with hepatitis A among the children attending the child care center?
What is the percentage of people who became ill with hepatitis A among the children attending the child care center?
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What is a characteristic of a proportion in measures of risk frequency?
What is a characteristic of a proportion in measures of risk frequency?
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What is the difference between a proportion and a rate in measures of risk frequency?
What is the difference between a proportion and a rate in measures of risk frequency?
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What is the formula for calculating a proportion in measures of risk frequency?
What is the formula for calculating a proportion in measures of risk frequency?
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What is the term for the number of cases or events occurring during a given time period in measures of risk frequency?
What is the term for the number of cases or events occurring during a given time period in measures of risk frequency?
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What is the term for the total number of persons or events, of which the numerator is a subset in measures of risk frequency?
What is the term for the total number of persons or events, of which the numerator is a subset in measures of risk frequency?
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What is the difference between a prevalence rate and an incidence rate in measures of risk frequency?
What is the difference between a prevalence rate and an incidence rate in measures of risk frequency?
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Study Notes
Measurement of Morbidity
- Morbidity is the condition of being diseased.
- Health is a state of complete physical, mental, and social well-being, not merely the absence of disease or infirmity (WHO, 1948).
Types of Data
- Data can be Numeric or Descriptive.
- Nominal-scale variables have values that are categories without any numerical ranking, such as county of residence.
- Ordinal-scale variables have values that can be ranked but are not necessarily evenly spaced, such as stage of cancer.
- Interval-scale variables are measured on a scale of equally spaced units, but without a true zero point, such as date of birth.
- Ratio-scale variables are interval variables with a true zero point, such as height in centimeters or duration of illness.
Frequency Distributions
- Frequency distributions have three features: central location, spread, and shape.
- A quick look at a graph reveals these features.
Measures of Risk Frequency Measures
- Ratio: a comparison of two quantities, where the numerator and denominator need not be related.
- Numerator: upper portion of a fraction.
- Denominator: lower portion of a fraction.
- Example: 32-7 = 25, so 5/25*100 = 20%.
Incidence and Prevalence
- Incidence: a measure of risk, or the number of new cases occurring in a population over a specified period of time.
- Prevalence: a measure of the burden of disease in a community, or the number of people with a disease living in a community.
- When there is a steady-state, prevalence and incidence are related.
- Prevalence increases with successful programs, but may give the appearance of failure.
Measures of Risk Frequency Measures
- Proportion: a comparison of a part to the whole, often expressed as a decimal, fraction, or percentage.
- Rate: a measure of the frequency with which an event occurs in a defined population over a specified period of time, often a proportion with an added dimension of time.
- Examples: attack rate, incidence rate, prevalence rate.
Examples of Morbidity Frequency Measures
- Attack Rate: measures the number of people who become ill after exposure to a risk factor.
- Incidence Rate: measures the number of new cases of a disease occurring in a population over a specified period of time.
- Prevalence Rate: measures the number of people with a disease living in a community at a specific point in time.
- Prevalence: measures the number of people with a disease living in a community over a specified period of time.
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Description
Test your understanding of epidemiologic data, including types of data, ratio, proportion, and rate. Learn how to describe data according to person, place, and time, and calculate incidence and prevalence rates. This quiz is based on a lecture from the Applied Nutrition Department on Nutritional Epidemiology and Research Methods.