From A for AGF Videoforschung to Z for zapping, the most important technical terms in video research are explained here.

Custom variables (c-variables) are used in streaming measurement. They are maintained by the providers on a per-video basis. The information for each video usage is transmitted in the streaming measurement process. Like broadcaster protocols in TV, they serve the purpose of transmitting programme-specific information such as the video length or title or information on the matching of TV programmes (see Matching).

Cable refers to the transmission of analog or digital television via copper or fiber-optic cables. The cable section from the cable head station to the property usually belongs to a cable network operator. This section is referred to as Network Level 3. The distribution line from the property to the residence is owned by many small cable network operators such as building societies, but also by the network level 3 cable network operator. This section is referred to as Network Level 4.

Calibration is the term used by AGF to refer to the process of adapting the views and net coverage values in the weighted and merged Video Streaming Panel to the level of the census measurement by means of statistical methods. Whereas the number of views is measured for the census measurement and the panel, the net coverage is only available in the panel and is extrapolated to the census level by means of a statistical estimation method.

In terms of the objective, calibration is similar to weighting: The purpose is to adapt the information collected from samples to the known external specifications of a full survey. In addition to the adjustment requirements dictated by the composition of the sample, calibration also serves to compensate for the design-related under-coverage of usage in the panel resulting from the non-coverage of at-work and other usage. The level variables of the census measurement only cover usage via the IP addresses assigned to Germany. To implement the calibration, the stream views must be aggregated to reach a sufficiently high number of cases case. These aggregations are known as calibration units. After the process of calculating the net coverage values at the level of the census measurement, these specifications are applied to generate a respondent-level data set, which forms the basis for analysis and planning.

Campaign control refers to the performance review of an already concluded advertising campaign on the basis of actually achieved reach values. It serves the purpose of measuring and evaluating the advertising impact.

Campaign planning involves the selection of suitable commercial breaks for the target group for an advertising campaign before they are broadcast. Suitable advertising environments are identified on the basis of past usage data . The indicators that serve to forecast the performance of the planning campaign can then be calculated with the aid of planning software. The indicators are net coverageaverage contactsaffinityCPM-C (cost per mille contacts), CPM-U (cost per mille users), GRP and contact distribution.

CAPI is an acronym that stands for computer-assisted personal interview. CAPI surveys are computer-assisted face-to-face interviews in which the interviewer reads the questions directly from the computer screen and enters the answers into the computer. Unlike a traditional face-to-face interview, the questionnaire is stored in the computer instead of being printed out on paper.

Catch-up TV is a form of VoD in which broadcasters make TV programmes available to users on the Internet for a certain period of time after the original broadcast. These programmes can usually be accessed by users free of charge.

CATI is an acronym that stands for computer-assisted telephone interview. CATI surveys are computer-assisted telephone interviews in which the interviewer reads the questions directly from the computer screen and enters the answers into the computer in the telephone studio. Unlike a traditional telephone interview, the questionnaire is stored in the computer instead of being printed out on paper.

CAWI is an acronym that stands for computer-assisted web interview. CAWI surveys are computer-assisted online surveys in which the questions are displayed one after the other to the interviewee on the computer screen and the answers are entered into the computer and stored there. Unlike a traditional survey, the questionnaire is stored in the computer instead of being printed out on paper.

Cell plan refers to a plan of characteristics used for the level control and quality assurance of the AGF Panel. For each state of Germany, it defines 54 cells in the reception levels of cable and satellite and 27 cells for the levels of terrestrial and IPTV. It is therefore called the 54/27 cell plan. These cells are subject to continuous target-actual comparisons.

The census is a population census conducted by the Statistical Offices of the German federal government and states that is meant to provide the most exact possible snapshot of basic data on the population, occupations and residential situation. The 2011 Census reflected the first Germany-wide census since reunification. It is said to be register-based because government data was used for this purpose. The census is conducted every 10 years; due to the pandemic, the last census took place in 2022.

Census measurement is a technical measurement that is based on a measurement library installed in a player that transmits usage data to a central server. Census measurement is a full survey of the use of all offerings used on each player and in which the Nielsen measurement library is implemented. The entire usage, thus including usage at the workplace or other usage locations, is included in the measurement. It can only be differentiated by global vs. domestic usage. 

In order for an offering to be included in the census measurement, a measurement library must be implemented in a given player. The measurement code identifies the usage (also called “tagging”), making it possible to calculate performance values and differentiate the offerings. Each provider is itself responsible for implementing the measurement code, also with regard to data protection regulations. Nielsen accepts each implementation and adherence to the standards defined by AGF centrally. 

The stream view is a key parameter of the census measurement of AGF. A stream view occurs when a video is started by the user on the player. The measurement employed by AGF always takes place on the player being used (client) and is therefore different from server-based measurement techniques that detect a view when only a request to the server is registered.

In addition to the information that usually must be directly present for a video view (meta data such as the URL or time stamp), additional characterizing variables are assigned to the video when tagging is employed. These variables are of a descriptive nature and are known in the measurement system as customer variables, which are assigned to each video to be measured or each advertising unit played on the tagged player via the provider’s content management system (CMS).

Channel sharing refers to the use of one frequency for several programmes, so-called window programmes. It requires the approval of the state media authorities.

CI is an abbreviation for Common Interface and describes a uniform physical interface in the set-top box. It enables CI modules to be inserted to activate encrypted programmes from different providers. CI Plus is a further development of CI and offers additional possibilities for programme providers. For example, HD+, a possibility to receive programmes in HD quality, is activated via the CI Plus slot of a television set or receiver.

Clustering refers to the condition of a sample in which several households per sampling point are available. No clustering is intended in the AGF Panel.

A coincidental check compares the results of two different studies with reference to the same point in time. Coincidental checks are used by AGF for the purpose of quality assurance of the Television Panel. See also Internal coincidental check and External coincidental check.

Combination analysis examines viewer identities across several programmes and days. For this purpose, users are identified for combinations of programmes or intervals of time that are linked with AND / OR / NOT.

Commercial breaks are collections of ad spots in blocks, which are then transmitted together. They usually consist of at least two ad spots, although single spots are also possible in exceptional cases.

Commercial breaks between programmes are commercial breaks between two consecutive TV programmes. They run between the end of one programme and before the beginning of a new programme.

The commercial break code contains important information about a commercial break for media planning purposes. The composition of such codes is binding for all advertising broadcasters that participate in the AGF. In the AGF system, the commercial break code consists of eight digits, where the different characters convey the following information: rate type (1-2), price group (3-4), planned broadcast hour (5-6), and break number (7-8). Any such eight-digit combination may only be used once for the same broadcaster within a broadcasting day.

This term refers to commercial breaks that run between two parts of a programme or movie such that the programme is interrupted by the commercial break.

Connected TV includes all TV sets that are actively connected to the internet. The internet connection can be directly on the set (see Smart TV), but also indirectly via internet-capable additional devices such as receivers/set-top boxes, streaming sticks/boxes or game consoles.

Constellation analysis examines the groups of persons who use a programme or a time interval together or not together. For this purpose, constellations are formed on the basis of the links AND / AND NOT.

Contact distribution indicates the number of persons attributable to the individual contact categories. Depending on the intensity of their media usage, the persons reached by a campaign may have different contact frequencies with the campaign. They are assigned to different contact classes according to their contact frequency. Contact distributions are also used as a gauge for assessing the advertising impact.

Contact total is the calculation of users across multiple analysis elements. Persons showing the performance values for multiple analysis elements are included not just once but multiple times.

This term refers to video streaming content. It analogous to a program in TV.

A content management system (CMS) is software for the collaborative creation, editing and organisation of content for websites or media libraries, for example. The majority of systems have a graphical user interface. Descriptive information on individual videos is transmitted from the content management systems of the video providers as part of the streaming measurement.

Control characteristics are defined household and person characteristics that are taken into account for the purpose of household selection and recruitment for the AGF Panel.

They consist of the following criteria:

  • State
  • District
  • Municipality size (BIK)
  • Reception level (AGF definition)
  • Household size
  • Age of the MEI
  • Education of the MEI
  • Presence of children in the household
  • Platform households (only for the satellite and cable levels)

Conurbations are clearly delimited geographical regions with a defined population density (urban agglomeration, metropolitan area, economic zone). They refer to one of the four types of BIK regions, which are sub-divided according to population size. Accordingly, conurbations are defined as large, population-dense agglomerations in which the core cities and surrounding areas have at least 750,000 inhabitants.

In the Federal Republic of Germany, there are a total of 14 conurbations that comprise 10.4% of municipalities and 31.3% of the population (according to BIK Regions 2020 with the territory status from 12/31/2020 and current population status from 12/31/2019).

From 2020 to 2022, AGF Videoforschung commissioned the Convergence Monitor, which Kantar has been conducting since 2008.

The studies can be found in the press releases.


Cookies are text files generated by websites that are stored in the computer browser of users who visit the websites. The cookies record the user’s personal settings and use of websites. This information makes it possible to identify the user and can be used to stored log-in data, for example. According to various court decisions (GDPR, German Federal Court of Justice), the use of cookies requires the user’s consent. The consent request is presented as soon as a user visits a website. AGF’s streaming measurement is no longer based on the use of cookies.

Cord cutters is frequently used term for a group of people or households that have a TV set but do not have a traditional reception channel (satellite, cable or terrestrial) and only use video in the form of VoD offerings and live streams via the Internet.

CPM-U is an acronym that stands for cost per mille (thousand) users. It indicates the amount of money that must be invested to reach a total of 1,000 unique persons in the target group at least once with an ad spot. The cost for an advertising campaign is calculated as the quotient of the total cost divided by the absolute net coverage of the campaign, multiplied by 1,000.

Crawls refer to the horizontal display of a running text at the bottom edge of the TV image. They are mainly used for current news headlines or sales offers and programming notes.

Cross-media refers to the linkage of different advertising channels such as TV and Internet, for example. In cross-media campaigns, advertising messages are delivered via several communication channels in order to reach consumers in different media genres. In this way, the impact synergies of the different kinds of media used can be better exploited, thus increasing the efficiency of an advertising campaign.

Cumulated net market share refers to the result of a cumulation and frequency analysis, specifically the net cumulation on the basis of the average market share (p-value method). The individual usage percentage or average market share of every person who has been reached by at least one programme is factored into the calculation. If the 0/1 method is used, this must be indicated.

In media planning, cumulation refers to the summation of gross reach, net coverage or average contacts according to a certain number of ad placements.

Cumulation and frequency analysis is a method for determining short-term and long-term viewer growth across any selection of elements such as programmes, commercial breaks or intervals of time.