Data Dictionaries

There are currently three different versions of the AHDSS data dictionary. They have been produced at different times and provide different information about AHDSS data.

AHDSS Core Data Dictionary - 2009 (564KB): This dictionary provides brief descriptions of all tables, fields, data labels, data types, and survey questions (where applicable) involved in the core AHDSS data collection process. It also indicates the relationships between these tables. This dictionary is in Microsoft Excel 2003 format. As such, each sheet in this file corresponds to a single table in the database.

AHDSS Detailed Data Dictionary - 2007 (7850KB): This dictionary provides a detailed account of all the tables, fields, data labels, and relationships in the AHDSS. It also includes copies of survey questionaires (i.e., data collection instruments), instructions for field workers on how to collect data, table statistics, and known data errors in the AHDSS. This dictionary is available in Portable Document Format.

AHDSS Overview Data Dictionary- 2004 (543KB): This dictionary provides a brief introduction to the AHDSS and the structure of the database. It includes a description of each table and lists the fields and data labels. It also indicates the relationships between these tables. This dictionary is available in Portable Document Format.

Data Definitions

This section lists common terms used in the AHDSS and will help to better understand the data dictionaries above.

Abortion: The following two cases are accepted in the definition of abortion:

·  Voluntary termination of pregnancy, i.e., when the mother decides to terminate her pregnancy before the 28th week (seven months) of pregnancy

·  Spontaneous abortion, i.e., problems/complications during pregnancy result in the mother having a miscarriage before the 28th week (seven months) of pregnancy

AHDSS: Agincourt Health and Demographic Surveillance Site

AHPU: Agincourt Health and Population Unit

Birth: The separation of offspring of the body of the mother

·  Live Birth: Any delivery where the baby is born alive (e.g., the baby cries, moves, breathes, and/or shows any other signs of life)

·  Still Birth: A baby who is born dead during or after the 28th week (seven months) of pregnancy

Death: The termination of life. The death of an individual will be recorded if the person was a member of a household in the census at the time of the death. The death form has to be completed for any permanent or temporary migrant person, live-born, or in-migrant who died in the period between the present and the last census visit.

De Facto Population:The population of residents who permanantly reside at a location (excludes temporary migrants).

De Jure Population: The population of residents who either permanantly or occasionly reside at a location (includes temporary migrant).

DSS: Demographic Surveillance Site

DSA: Demographic Surveillance Area

External In-Migration: The in-migration of a person in a household coming from a place other than the study area.

External Out-Migration: The out-migration of a person to a household that it is not in the study area.

Households: A group of people who reside and eat together, plus the linked temporary migrants who would eat with them on return. This is a de jure household definition because it is more closely related to links of responsibility within the household, as opposed to a de facto household definition which more closely matches the co-residential household, as used in the national census. One implication of the Agincourt definition in data collection is that when a field worker encounters a permanent out-migrant this person becomes removed from the household resident list, whereas a temporary migrant is retained on the household list.

Individuals: Every single person that has been identified as living in the area. This person can have different residential status mainly, permanent and temporary migrant.

Internal In-Migration: The in-migration of a person in a household coming from another household in the study area.

Internal Out-Migration: The out-migration of a person to a household that it is in the study area.

In-Migrant: A person who is new in a household since the last census.  It is accepted by the head of the household that s/he intends to stay permanently in that new household.

Locations:  A geographical point defined using GIS where there is at least one dwelling.

Marital Status: The different statuses that a person can have by living or ceasing to live with another person.

·  Single: Marital status of a person who has never been married or lived with another person

·  Married (Formal marriage):  Marital status wherein a single person has fulfilled all the requirements for a community (social, religious, legal) to recognize that s/he is permanently sharing her/his life with another concrete person 

·  Informal Union: Marital status wherein a person is living with someone else without fulfilling any requirement

·  Widowed: Marital status wherein a person has finished the marriage or union because of the death of the partner

·  Divorced: Marital status wherein a person has finished a union with his/her partner by either going to the court or a lawyer and getting all documents that formalize the end of that union OR  performing a socially accepted ceremony that ends that union (e.g., a woman’s family pays back lobola to the husband’s family in which case the woman is called Xivuya (divorced))

·  Separated: Marital status wherein a person has finished the union by not sharing the same house with the former partner in a definitive way

·  Remarried: Marital status wherein a person has re-initiated a marriage after being widowed or divorced

Migration Reconciliation: Involves the tracking of internal migrants to link up the places of origin and destination for each move within the field-site. The process involves checking that the person leaving the place of origin and entering the place of destination is the same person. This makes the data cleaner because it avoids the possibility of having the same person registered in two places at the same time and also enables people to keep the same unique identifier when they move. The migration data in the database is then much more accurate and complete because people can be followed when they move, which improves the study of households’ and individuals’ migration behaviour. It also facilitates longitudinal studies, like cohort studies or clinical trials, because it enables the follow up of individuals who move within the site, so a person enrolled onto treatment or surveillance can remain a part of the study when they migrate within the study area.

Out-Migrant: A person who was in the household during the last census and has since moved out of that household.

Permanent Migrant: A person who enters or leaves a household with a permanent intention of entering or leaving. This definition closely follows the classic definition that migrants are people who experience a change in residence. This includes people who leave the index household and establish a household or join a household elsewhere. A key feature is that the destination household becomes the new home base for the migrant. The main reasons given in the Health and Demographic Surveillance System for permanent migration are: “union formation or dissolution”; “to live with another” and “new dwelling for household”.  A permanent migrant is either in- or out-migrated.  An out-migrant is removed from a household (i.e. a social group) and a dwelling (i.e. the physical infrastructure), and an in-migrant is moved into a household and dwelling. Technically, a migrant is added or removed from a household by starting or ending a membership episode in the household, and simultaneously starting or ending a residence episode at the dwelling. The salient details of the migration event, e.g. “date of move”, “origin” or “destination”,  are captured and stored in the migration table.

Status Observation: This refers to a specific point in time to describe if an individual or household was or was not observed at the last time it was visited.

SES: Socio Economic Status

Temporary Migrant: A household member who is away the majority of time, but retains a significant link to their base household. In analysis, a six month per year cut –off point was chosen to differentiate ‘temporary migrants’ from ‘local residents’. Thus, people who are referred to as temporary migrants were absent from the household for more than six months of the year preceding observation, but who considered the index household to be their home base.

Temporary Migration: A status based on ‘resident months’ status which records the amount of time each person is physically present in the household during the year preceding the census interview. The fieldworker hears the account of a person’s residence pattern and adds the residence episodes together, rounds this up to a whole number and records this as the number of months that a person was present in the previous year. This variable, i.e. ‘resident months’ has been updated in successive census rounds in 1992, 1995, 1997, 1999, and annually since then.  Based on the ‘resident months’ variable a fieldworker also records a  ‘residence status’ variable. This is derived from ‘resident months’ but contains slightly more information. “Resident status” has four categories, namely, ‘Local resident’, if ‘resident months’ is between six and twelve months; ‘Temporary Migrant’, if ‘resident months’ is less than six and the reason for absence is work-related; ‘Other Temporary Migrant’ if ‘resident months’ is less than six and the reason is not work-related; lastly, a ‘Visitor’ is if a person was present at the census but should not be considered part of the household. A child born or in-migrated in the year prior to the census is considered a ‘local resident’ if the household informant considered their residence to be permanent despite the number of resident months.

Union: Two people are considered to be in a union if they are living together. The creation of a new household constitutes a new union, rather than the time the couple began living together.

Villages: A group of geographically, well-defined locations. There are political and research villages:

·  Political villages are those recognized by the Municipality and Province governments

·  Research villages are those defined by AHPU for work purposes