adjustments. Statistical calculations that allow the comparison of different groups (when the difference may affect what you are studying) as though they are alike. Differences in populations or subgroups make it difficult to make comparisons; adjustments remove the influence of a specific factor (e.g., age, gender, race, or disease status) from the analysis.

aggregated data. Information, usually summary statistics, that is summed or presented together to prevent the identification of individuals.

AIDS (acquired immunodeficiency syndrome). The condition that results from HIV infection and is marked by the presence of opportunistic infections that do not affect persons with healthy immune systems.

bar graph (vertical). A type of figure in which categories of variables (displayed on a horizontal baseline) are compared by amount, frequency, or magnitude (labeled on a vertical axis). (Bar graphs may also be horizontal.)

behavioral data. Data collected from studies of human behavior that is relevant to disease risk. Relevant behaviors for HIV risk may include sexual activity, substance use, sharing of drug paraphernalia, condom use, or responses to primary and secondary prevention messages.

capability. The extent to which a provider’s services are geographically and physically accessible, culturally appropriate, and available at convenient times.

capacity. The amount of services a provider can deliver (i.e., the number of service units and the estimated number of clients who can be served).

CARE Act (Ryan White Comprehensive AIDS Resources Emergency Act). The primary federal legislation created to address the needs for health and support services among persons living with HIV/AIDS and their families in the United States; enacted in 1990 and reauthorized in 1996.

case. A condition, such as HIV infection (e.g., an HIV case) or AIDS (e.g., an AIDS case) diagnosed according to a standard case definition.

case fatality. The number of deaths among persons with a diagnosis of the disease of interest. Usually expressed as a rate (number of deaths after disease onset or diagnosis divided by the number of persons with the disease); measures the effect of the disease on persons with a diagnosis.

chief elected official (CEO). The official recipient of Title 1 funds within the EMA, usually the mayor or the chair of the county governing unit (e.g., board of supervisors).

community planning group. A group of persons who represent, or have interests in, a given community and who work in partnership with health departments to design local prevention plans to meet the needs of persons at risk for, or infected with, HIV.

community-based organization (CBO). An organization that provides services to locally defined populations, which may include persons infected with, or affected by, HIV.

comorbidity. The coexistence of a disease or illness and HIV infection in one person (e.g., an HIV-infected person who also has TB).

comprehensive planning. The process used to determine how HIV services will be organized and delivered. Comprehensive HIV services planning requires planning councils and consortia to answer 4 questions: (1) Where are we now? (2) Where should we be going? (3) How will we get there? (4) How will we monitor our progress?

confidence interval (CI). A range of values for a measure that is believed to contain the true value at a specified level of certainty (e.g., 95%).

confidentiality. The treatment of information that an individual or institution has disclosed in a relationship of trust, with the expectation that the information will not be divulged to others in ways that are inconsistent with the individual’s or institution’s understanding when the individual or institution provided the information. It encompasses access to, and disclosure of, information in accordance with requirements of state law or official policy. For HIV/AIDS surveillance data, confidentiality refers to the protection of private information collected by the HIV/AIDS surveillance system.

continuum of care. A coordinated delivery system, encompassing a comprehensive range of health and social services that meet the needs of people living with HIV at all stages of illness.

convenience sampling. A sampling technique that relies upon selecting people who are more easily accessible at the time (e.g., persons at a group meeting or in a clinic when a researcher happens to be there). The advantage of convenience sampling is that it is easy to carry out. The weakness is that the findings may not be representative of the entire community.

core epidemiologic questions. The questions in an epidemiologic profile that must be answered by all prevention and care grantees, regardless of HIV morbidity in their areas.

cumulative cases. The total number of cases of a disease reported or diagnosed during a specified time. Cumulative cases can include cases in people who have died.

cumulative incidence rate. The total number of persons who experience the onset of a disease during a specified period among all people at risk for the disease. A cumulative incidence rate is calculated by dividing cumulative incidence for a specified period by the population in which cases occurred during that period. A multiplier is used to convert the resulting fraction to a number over a common denominator (often 100,000).

eligible metropolitan area (EMA). A metropolitan statistical area that qualifies for Title I funding by reaching a certain threshold of AIDS cases. EMAs may cover 1 city, several cities or counties, or more than 1 state.

epidemic curve. A type of line graph that shows the distribution of disease onset. Time is plotted on the horizontal (x) axis; the number of cases is plotted on the vertical (y) axis.

epidemiologic profile. A document that describes the HIV/AIDS epidemic in various populations and identifies characteristics both of HIV-infected and HIV-negative persons in defined geographic areas. It is composed of information gathered to describe the effect of HIV/AIDS on an area in terms of sociodemographic, geographic, behavioral, and clinical characteristics. The epidemiologic profile serves as the scientific basis from which HIV prevention and care needs are identified and prioritized for a jurisdiction.

epidemiology. The study of the distribution and determinants of health-related states or events in specified populations and the application of this study to the control of health problems.

estimate. In situations in which precise data are not available, an estimate may be made on the basis of available data and an understanding of how the data can be generalized to larger populations. In some instances, national or state data may be statistically adjusted to estimate local conditions. Good estimates are accompanied by statistical estimates of error (a confidence interval), which describe the limitations of the estimate.

grantee. The recipient of HIV prevention or CARE Act funds. For HIV prevention funds, the state or local health department is referred to as the grantee. For CARE Act funds, the chief elected official (CEO) of each EMA is the official grantee for Title I funds. Under Title II, the governor designates a state agency (usually the state health department) as the grantee.

HIV (human immunodeficiency virus). The virus that causes AIDS. Persons with HIV in their system are referred to as HIV infected.

HIV Care Consortium. An association of public and private nonprofit providers of health support services and community-based organizations that plans, develops, and delivers services for people living with HIV. The CARE Act authorizes states to use Title II funds to establish consortia in “areas most affected by HIV disease.”

HIV primary medical care. Medical evaluation and clinical care that is consistent with US Public Health Service guidelines for the treatment of HIV/AIDS.

HIV/AIDS surveillance. The systematic collection, analysis, interpretation, dissemination, and evaluation of population-based information about persons with a diagnosis of HIV infection and persons with a diagnosis of AIDS.

incidence. The number of new cases in a defined population during a specific period, often a year, which can be used to measure disease frequency. It is important to understand the difference between HIV incidence and reported HIV diagnoses. Because the results of anonymous tests are not included and therefore not all diagnoses of HIV infection are included, HIV surveillance data do not represent incident cases.

incidence rate. The number of new cases in a specific area during a specific period among persons at risk in the same area and during the same period. Incidence rate provides a measure of the effect of illness relative to the size of the population. Incidence rate is calculated by dividing incidence in the specified period by the population in which cases occurred. A multiplier is used to convert the resulting fraction to a number over a common denominator (often 100,000).

interpretation. The explanation of the meaning of the data. For example, interpreting a trend in the number of HIV cases diagnosed during a 5-year period enables a planning group to assess whether the number of cases has increased or decreased. However, groups should use caution in interpreting trends that are based upon small increases or decreases.

jurisdiction. A geographic area in which a government agency conducts surveillance or provides public health services.

line graph. A type of figure used to display the changes in a particular variable over time. Values are recorded periodically as points on a graph and then connected as a line to show a trend.

mean. The sum of individual values in a data set divided by the total number of values. The mean is what many people refer to as an average.

median. The middle value in a data set. Typically, approximately half the values will be higher, and half will be lower. The median is useful when a data set has unusually high or unusually low values, which can affect the mean. It is also useful when data are skewed, meaning that most of the values are at one extreme or the other.

morbidity. The presence of illness in the population.

mortality. The total number of persons who have died of the disease of interest. Usually expressed as a rate, mortality (total number of deaths over the total population) measures the effect of the disease on the population as a whole.

needs assessment. The process of gathering and analyzing information from a variety of sources to determine the current status and the unmet needs for HIV prevention or care among a defined population or in a geographic area.

no identified risk (NIR). Cases in which epidemiologic follow-up has been conducted, sources of data have been reviewed―which may include an interview with the patient or provider―and no mode of exposure has been identified. Any case that continues to have no reported risk 12 or more months after the report date is considered NIR

no reported risk (NRR). Cases in which risk information is absent from the initial case report because the information had not been reported by the reporting source, had not been sought, or had not been found by the time the case was reported. Cases may remain NRR until epidemiologic follow-up has been completed and potential risks (exposures) have been identified. If risk has not been identified within 12 months of being reported as NRR, the case may be considered NIR.

percentage. A proportion of the whole, in which the whole is 100.

prevalence. The total number of cases of a disease in persons not known to have died in a given population at a specific time. Prevalence does not indicate how long a person has had a disease and cannot be used to calculate rates of disease. It can provide an estimate of risk for a disease at a specific time. For HIV/AIDS surveillance, prevalence refers to living persons with HIV disease, regardless of time of infection or date of diagnosis. Note the difference between prevalence of a condition in the population and the prevalence of cases, namely, that a case must be diagnosed according to a definition.

probability sampling. A sampling technique that relies upon random selection to select persons from a defined population; all persons have a known chance of selection. Types of probability samples include simple random sample, systematic random sample, and stratified sample.

probability (P) value. The probability that a statistical result (an observed difference or relationship) could have occurred by chance alone. Statistical results usually are regarded as significant if there is less than 5% probability that the observed difference or relationship was due to chance alone. In such situations, the P value is said to be less than .05 (P <.05).

proportion. A portion of a complete population or data set, usually expressed as a fraction or percentage of the population or data set.

qualitative data. Information from sources such as narrative behavior studies, focus group interviews, open-ended interviews, direct observations, ethnographic studies, and documents. Findings from these sources are usually described in terms of common themes and patterns of response rather than by numeric or statistical analysis. Qualitative data often complement and help explain quantitative data.

quality of life. A subjective measure of the degree to which persons affected by a specific disease, injury, or form of treatment perceive themselves to be able to function physically, emotionally, and socially. Quality of life is useful for the planning of health services.

quantitative data. Numeric information (e.g., numbers, rates, and percentages).

range. The largest and smallest values in a data set.

rate. A measure of the frequency of an event or a disease compared with the number or persons at risk for the event or disease.

ratio. A way of showing the relative size of 2 numbers. The first number is divided by the other number to derive the ratio. The ratio may be expressed as a fraction (e.g., ⅔), or the 2 numbers may be separated by a colon (e.g., 2:3).

raw data. Data that are in their original form (i.e., not coded or analyzed).

reliability. Refers to the consistency and dependability of a data-collection instrument or measure. For example, if you repeat a blood test 3 times on the same specimen and the results are the same each time, the test is said to be reliable.

reporting delay. The time between a diagnosis of HIV infection or AIDS and the receipt of the report by the health department.

representative. A sample that is similar to the population from which it is drawn and thus can be used to draw conclusions about the population.

sample. A group of people selected from a total population with the expectation that studying this group will provide important information about the total population.

seroprevalence. The number of persons in a defined population who test positive for HIV based on HIV testing of blood specimens. (Seroprevalence is often presented either as a percentage of the total specimens tested or as a rate per 100,000 persons tested.)

service area. CDC jurisdictions and HRSA service areas or planning regions.

sociodemographic factors. Background information about the population of interest (e.g., age, sex, race, educational status, income, geographic location). These factors are often thought of as explanatory because they help us to make sense of the results of our analyses.

socioeconomic status (SES). A measure of social and economic factors that helps to describe a person’s standing in society (e.g., income level, relationship to the national poverty line, educational achievement, neighborhood of residence, home ownership).

stratification. A technique for dividing data into homogenous groups (strata).

Title I (CARE Act). Provides formula and supplemental grants to EMAs that are disproportionately affected by the HIV epidemic.

Title II (CARE Act). Provides formula grants to states, the District of Columbia, Puerto Rico, and eligible US territories to improve the quality, availability, and organization of health care and support services for people living with HIV and their families.

trend. A long-term movement or change in frequency, usually upward or downward; may be presented as a line graph.

triangulation. Synthesis of data to compare and contrast the results of different kinds of research that address the same topic.

validity. The extent to which a measurement is appropriate for the question being addressed or measures what it is intended to measure (may be applied, for example, to an instrument for data collection or specific questions in a survey).

year of diagnosis. The year in which a diagnosis of HIV infection or AIDS was made.

year of report. The year in which a person with a diagnosis of HIV infection or AIDS was reported to the health department.

years of potential life lost (YPLL). The number of years that persons would have lived if they had not died of the disease of interest. Calculated by summing the years that persons would have lived had they attained normal life expectancy, YPLL measures the effect of mortality on the community.

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