Similar to listed samples, this methodology selects only business numbers from the database of listed phone numbers. Since almost all businesses choose to be listed in directories, there are very few that are excluded from the selection process.
These are referred to as Census overlay samples by ASDE. The samples are drawn on the basis of maximizing a demographic or economic characteristic by selecting those regions that are above a given threshold for that characteristic.
As an example: “Zip codes within the state of Florida, where the percentage of households with children under 18 is above X%”. These samples can be very useful when applied carefully and only when it is necessary to improve on low incidence rates and when no other appropriate frames are available.
Directory Listed Samples
This methodology draws numbers directly from the telephone directory listings. We use the best available electronic listings for these samples.
ASDE generates the sample numbers in two ways, the traditional RDD method and the ASDE enhanced RDD methodology.
A method of identifying the households to be contacted for a telephone interview. Either all the digits of the telephone number are randomly generated, or numbers are randomly selected from a directory and the last one or two digits are replaced by random numbers. (Source: Oxford Dictionary of Business)
A group of individuals or cases from a particular population. Sampling and statistical inference are used in circumstances in which it is impractical to obtain information from every member of the population, as in biological or chemical analysis, industrial quality control, or social surveys. The basic sampling design is simple random sampling, based on probability theory. In this form of random sampling, every element of the population being sampled has an equal probability of being selected. In a random sample of a class of 50 students, for example, each student has the same probability, 1/50, of being selected. Every combination of elements drawn from the population also has an equal probability of being selected. Sampling based on probability theory allows the investigator to determine the likelihood that statistical findings are the result of chance.
More commonly used methods which are refinements of this basic idea, are stratified sampling (in which the population is divided into classes and simple random samples are drawn from each class), cluster sampling (in which the unit of the sample is a group, such as a household), and systematic sampling (samples taken by any system other than random choice, such as every tenth name on a list). (Source: Encyclopedia Britannica)
Canada Geographical Definitions
Census Division (CD)
Census division (CD) is the general term applied to areas established by provincial law which are intermediate geographic areas between the municipality (census subdivision) and the province level. Census divisions represent counties, regional districts, regional municipalities and other types of provincial legislated areas. (Source: Statistics Canada)
Census Metropolitan Area (CMA) and Census Agglomeration (CA)
A Census Metropolitan Area (CMA) is a very large urban area (known as the urban core) with adjacent urban and rural areas (known as urban and rural fringes) which have a high degree of social and economic integration with the urban core. A CMA has an urban core population of at least 100,000, based on the previous census. Once an area becomes a CMA, it is retained as a CMA even if the population of its urban core declines below 100,000. All CMAs are subdivided into census tracts. A CMA may be consolidated with adjacent Census Agglomerations (CAs) if they are socially and economically integrated. This new grouping is known as a consolidated CMA and the component CMA and CA(s) are known as the Primary Census Metropolitan Area (PCMA) and Primary Census Agglomeration(s) (PCA(s)). A CMA may not be consolidated with another CMA. (Source: Statistics Canada)
Census Subdivision (CSD)
Census Sub-Division (CSD) is the general term applying to municipalities (as determined by provincial legislation) or their equivalent (for example, Indian reserves, Indian settlements and unorganized territories).
In Newfoundland, Nova Scotia and British Columbia, the term also describes geographic areas that have been created by Statistics Canada in cooperation with the provinces as equivalents for municipalities for the dissemination of statistical data. (Source: Statistics Canada)
Dissemination Area (DA)
Small area composed of one or more neighbouring blocks, with a population of 400 to 700 persons. All of Canada is divided into dissemination areas.
The dissemination area (DA) is a small, relatively stable geographic unit composed of one or more blocks. It is the smallest standard geographic area for which all census data are disseminated. DAs cover all the territory of Canada.
Economic Region (ER)
An economic region (ER) is a grouping of complete census divisions (with one exception in Ontario). Prince Edward Island and the two territories each consist of one economic region. Economic regions are used to analyze regional economic activity. (Source: Statistics Canada)
Federal Electoral District (FED)
A Federal Electoral District (FED) refers to any place or territorial area entitled to elect a representative member to serve in the House of Commons (source: Canada Elections Act, 1990). There are currently 308 electoral districts. For more information, visit the Elections Canada website.
Forward Sortation Area (FSA)
The Forward Sortation Area is the identifier for the first three characters of any Canadian postal code. It is the basis for sorting mail. It identifies an area within a province, region, or territory in Canada. The first character in the FSA identifies any one of eight provinces, three territories and eight districts or geographic regions in Ontario and Quebec. For example, all postal codes that begin with the letter “A” refer to Newfoundland, while all codes that begin with the letter “T” refer to Alberta. The second and third characters in the FSA help to identify the exact area in a city or town (or other geographic location) where mail will be delivered. Each FSA has a specific boundary that allows businesses to define a market or sales area. (Source: Canada Post)
Standard Geographical Classification
The Standard Geographical Classification (SGC) is Statistics Canada’s official classification of geographic areas in Canada. The SGC provides unique numeric identification (codes) for three types of geographic areas. These are provinces and territories, census divisions (CDs) and census subdivisions (CSDs). The three geographic areas are hierarchically related. (Source: Statistics Canada)
US Geographical Definitions
Census Regions and Divisions
Census Regions are groupings of states that subdivide the United States for the presentation of data. There are four regions – Northeast, Midwest, South and West. Each of the four census regions is divided into two or more census divisions. Prior to 1984, the Midwest region was named the North central region. From 1910, when census regions were established, through the 1940’s, there were three regions – North, South, and West.
Census Divisions are groupings of states that are subdivisions of the four census regions. There are nine divisions, which the Census Bureau adopted in 1910 for the presentation of data. These include New England Division, Middle Atlantic Division, East North Central Division, West North Central Division, South Atlantic Division, East South Central Division, West South Central Division, Mountain Division, Pacific Division. (Source: US Census Bureau)
The primary political divisions of most States are termed “counties”. In Louisiana, these divisions are known as “parishes”. In some states, there are cities that are independent of any county organization and thus constitute primary divisions of their states. These cities are known as “independent cities” and are treated as equivalent to counties for statistical purposes. The District of Columbia has no primary divisions, and the entire area is considered equivalent to a county for statistical purposes. Each county and county equivalent is assigned a three-digit FIPS code that is unique within each State. These codes are assigned in alphabetical order of county or county equivalent within a State, except for the independent cities, which follow the listing of counties. (Source: US Census Bureau)
Congressional Districts (CD)
Congressional districts are the 435 areas from which persons are elected to the U.S. House of Representatives. After the appointment of congressional seats among the States, based on census population counts, each State is responsible for establishing CDs for the purpose of electing representatives. Each CD is to be as equal in population to all other CDs in the State as practicable, based on the decennial census counts. (Source: US Census Bureau)
Metropolitan Area (MA)
The general concept of a metropolitan area (MA) is one of a large population nucleus, together with adjacent communities that have a high degree of economic and social integration with that nucleus. Some MAs are defined around two or more nuclei.
The MA classification is a statistical standard. Each MA must contain either a place with a minimum population of 50,000 or a Census Bureau-defined urbanized area and a total MA population of at least 100,000. An MA comprises one or more central counties, or may include one or more outlying counties that have close economic and social relationships with the central county. (Source: US Census Bureau)
Metropolitan Statistical Area (MSA)
Metropolitan Statistical Areas are relatively freestanding MAs and are not closely associated with other MAs. These areas typically are surrounded by non metropolitan counties.
Consolidated and Primary Metropolitan Statistical Area (CMSA and PMSA)
If an area that qualifies as an MA has more than one million persons, primary metropolitan statistical areas (PMSAs) may be defined within it. PMSAs consist of a large urbanized county of cluster of counties that demonstrates very strong internal economic and social links, in addition to close ties to other portions of the larger area. When PMSAs are established, the larger area of which they are component parts is designated a consolidated metropolitan statistical area (CMSA). (Source: US Census Bureau)
Zip Codes are administrative units established by the United States Postal Service (USPS) for the distribution of mail. ZIP Codes serve addresses for the most efficient delivery of mail, and therefore generally do not respect political or census statistical area boundaries. ZIP Codes usually do not have clearly identifiable boundaries, often serve a continually changing area, are changed periodically to meet postal requirements, and do not cover all the land area of the United States. ZIP Codes are identified by five-digit codes assigned by the USPS. The first three digits identify a major city or sectional distribution center, and the last two digits generally signify a specific post office’s delivery area or point. (Source: US Postal Service)