Glossary of Terms

Content Area: Content areas are broad categories of data on a specific topic such as cancer, asthma or birth defects.

Indicator: Indicators are data which help show trends for public health concerns such as blood lead levels in children, specific cancers, or ozone levels. Indicators help us answer the question of how well we are doing when comparing data over time or when comparing with other counties or states. You can search for indicators that are part of the Environmental Public Health Tracking Network here:

Measure: Measures are specific to an indicator, for example the percent of adults ever diagnosed with asthma, or age-adjusted rates of leukemia. An indicator can have several measures that provide information based on age, sex, time, or location.

Metadata: Metadata describe information about a dataset. They provide information about the content, quality and context of the data. Metadata are important for sharing data and helping you decide if it meets your needs.

Incidence: Incidence is expressed as a rate, and is a measure of the risk of a medical condition occurring in a population within a specific period of time. It only measures new cases or diagnoses of that disease during that time period. For example, if a population has 1,000 people and 28 are diagnosed with cancer over one year, the incidence rate is 2.8% per year.

Prevalence: Prevalence refers to the total number of cases of a disease in a specific period of time, not just the new diagnoses. It is used to measure how widespread a disease has become and the ratio between those who are already infected and those who are at risk.

Number (Count): The number (or count) indicates the total number of occurrences such as hospitalizations, emergency department visits, or disease diagnoses. Numbers provide information on the magnitude of the overall issue. They do not provide information on unique individuals or on the risk to a certain population.

Crude Rate: Rates provide information on probability and underlying risk in a population. They are calculated by dividing the total number of cases in a given period of time by the total number of people in the population during that same period of time.

Age-adjusted Rate: Age-adjusted rates are rates that would have existed if the population being studied had the same age distribution as a “standard” population. These rates are useful when comparing two populations that have different age distributions. For example, a state with a relatively older population generally will have higher crude rates for cancer deaths. The age-specific rates are adjusted to the age distribution in a standard population, usually the 2000 U.S. standard population.  

Age-specific Rate: Similar to a crude rate, an age-specific rate is calculated within an age group (such as adults 35-44 years of age).

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