6.5 Medição das audiências

Cresce o movimento de «apoio» ao telemóvel da MediaAudit

Relativamente a este caso, surgem notícias de que há cada vez mais apoio para o sistema da MediaAudit, o que não pode deixar de ser interpretado como uma espécie de cartão amarelo ao PPM - afinal a indústria não está tão convencida como parece.

Agora é a CBS Radio, depois da Radio One e da Cox: «"We are impressed with how quickly The Media Audit /IPSOS team is hitting its milestones in bringing the radio industry an alternative electronic ratings service. The Media Audit/Ipsos formally applied to the evaluation committee in December and is now preparing for a market test 3 months later. That's impressive. Clearly they have a plan and they know what they are doing." commented Hollander.» (http://www.radioink.com/headlineentry.asp?hid=132847&pt=inkheadlines)

Os prazos para o PPM

«Arbitron said the conversion from its current paper-based diary method would begin with Houston in July, with plans to convert the top 10 radio markets by the fall of 2008 and the top 50 within three years following that. ». No entanto, «To date, only two broadcasters - Spanish Broadcasting and Beasley Broadcasting - have committed to its use, even though most of Madison Avenue's biggest radio buyers have endorsed the service».

Além disso: «Some influential radio broadcasters, especially, Clear Channel Communications, have been fishing for an alternative to the PPM. Clear Channel recently issued a request for proposals for a new, state-of-the-art electronic radio audience measurement system, and last week narrowed the list of candidates to three finalists including Arbitron, Mediamark Research Inc. and The Media Audit, all of whom have some form of passive radio audience measurement. The Clear Channel-lead initiative, which includes Madison Avenue executives, is expected to make a final selection and begin a field test soon».

Fonte: «Arbitron Begins Portable People Meter Rollout», Media Daily News, Joe Mandese, Tuesday, Mar 14, 2006 8:01 AM EST

(ACT) MediaAudit ataca PPM com o seu telemóvel

«As their system is being tested in England, the Media Audit is now requesting permission from Houston radio station owners to encode their signals in order to conduct a test of their Smart Cell Phone system of electronic media measurement.»

Mais: «Radio One Houston properties are the first Houston stations to agree to encode their signals as part of a series of tests The Media Audit will be conducting with its Smart Cell Phone media monitor (...). Abernethy said, "It is well recognized that the radio industry needs to move to an electronic measurement. I appreciate the efforts that Arbitron has put into testing its proposed solution. At the same time, we need more information and more ways to sell the advertising strengths of radio. The Media Audit/Ipsos solution addresses this need for more information as it includes multiple media platforms as well as retail information. I am encouraged with The Media Audit/Ipsos Smart Cell Phone solution as it addresses many concerns that we and others in the industry share about the potential flaws in electronic measurement." (Radio Ink, «Radio One Agrees To Encode Houston Stations For Smart Cell Phone Media Measurement Testing»).

Why Smart Cell Phones are a Better Media Measuring Device

The cell phone is an integral part of people's daily lives, which makes it the ideal mode for passively monitoring activities from media exposure to retail activity. Our proposed passive measurement system incorporates the latest technology into smart phones for measuring radio, television, radio and television streaming via the internet, cable, satellite television, billboards and other out-of-home media.

Cell phones are a part of our culture. We take them everywhere we go. A popular online web site notes, "With high levels of mobile telephone penetration, a mobile culture has evolved, where the cell phone becomes a key social tool." Cell phones have been adopted faster than any other consumer product or service from its inception to its penetration in the market. In less than twenty years, mobile phones have gone from being rare and expensive pieces of equipment used by businesses to a pervasive low-cost personal item.

Over the past ten years, the number of Americans carrying a cell phone has increased by 500 percent for an estimated 200 million people. Based on this estimate, 70% of Americans have a cell phone. In addition, a recent NPD survey shows Smart Phone penetration up seven percent during the third quarter of 2005.

Using a smart phone that carries specially developed software from Ipsos, this solution offers a number of unique advantages over other proposed media measurement devices:

- The cell phone is a familiar device. It is more likely that respondents will carry around a cell phone than other types of proposed meter devices.
- Smart Phones can continue to monitor media exposure in places where users would be required to turn their cell phones off. Users can put them on "quiet mode" wherein the phone won't ring but can be used for other functions that includes the ability to monitor media exposure. The "always on" feature will result in greater accuracy in the data.
- Finally, cell phones are gaining use for playing music, audio and video downloading, playing interactive games, and even conducting credit card transactions.
- Continuing advances in cell phone technology and increases in usage underscores why The Media Audit/Ipsos Smart Phone will be able to measure radio audiences that a pager type meter will not be able to measure.» (fonte: Radio Marketing Nexus, Audience Measurement by Smart Phone?, Posted by Mark Ramsey on February 23, 2006)

(acT) Fraude nas audiências espanholas; mais cedo ou mais tarde...

A empresa que realiza as audiências em Espanha comunicou que suspendeu o processo, depois de ter encontrado indícios de fraude. A Cadena COPE reagiu, dizendo ter realizado uma investigação que o prova...

«The only details revealed are buried in careful language, the lawyers obviously consulted. AIMC “detected the existence of false interviewers within the field-work groups attempting to manipulate the survey data.”  The AIMC Board, said the release, continues to investigate. Pending that, the first survey wave (January through March) might be called off. Wednesday night, early by Spanish custom but yet quite dark, Radio COPE’s Lantern program announced an investigation by its journalists, led by sports director Jose Antonio Abellán, had been conducted to “demonstrate fraud” within the EGM. The network had, by its own admission, infiltrated its “journalists” into the field-work groups.»

Mais: «Madrid, 10 de Marzo de 2006. La Junta Directiva de la Asociación para la Investigación de los Medios de Comunicación (AIMC), responsable de la realización del Estudio General de Medios (EGM) en su reunión de hoy 10 de marzo de 2006, ha decidido por unanimidad incoar expediente de sanción a la Cadena COPE con propuesta de expulsión por faltas muy graves atendiendo a lo indicado en los estatutos de la asociación».

«La Cadena COPE pide, a la luz de los resultados de este trabajo de investigación, que se ponga en marcha de forma inmediata una auditoria sobre el sistema de medición de las audiencias que utiliza el EGM por el bien de las empresas, de los anunciantes y de la audiencia que tiene la radio española»

O sistema Radiocontrol (GfK)

O grupo GfK tinha vários sistemas de medição electrónica, desde o sistema Eurisko, passando pelos relógio "radiocontrol" e "mediawatch".

Sobre o Radiocontrol, sabe-se que: «has been used in the UK for measurement of exposure to radio and TV by the Wireless Group since 2003. In the UK and across Europe, the technology has been used to measure in-home and out-of-home TV viewing of ‘hard to reach’ groups, and for cross media research on behalf of leading media agencies and international media owners.» De acordo com os seus responsáveis, «RADIOCONTROL is the electronic audience measurement system developed by Telecontrol, part of the GfK Group. RADIOCONTROL is a passive, electronic audience measurement device built into a wristwatch. Respondents are typically asked to wear the watch for a week during which time a built-in microphone records a short, four-second sequence of sound during each minute of the surveyed week. These sounds are stored not as sound files, but in a heavily compressed, digitised format, representing no more than audio ‘fingerprints’ of the original files. At the end of the surveyed week, the data from the watches are downloaded, and these listening records matched to a set of audio samples of every TV station and radio station monitored in the survey. If an audio fingerprint stored on the watch during a particular minute matches the sound sample of a particular station during the same minute, we may infer that this watch was exposed to this station at this time. By matching the sound samples recorded each minute by each watch to the stations’ broadcast output, it is possible to build up a minute-by-minute record of each respondent’s TV and radio listening. After extensive laboratory and field tests, the technology has been used in the national radio audience measurement system in Switzerland since 2000. In Great Britain, the system has been tested and trialled since 2001. In March 2003, The Wireless Group commissioned GfK to launch a continuous national survey of viewing and listening using RADIOCONTROL, from which the data for this analysis are drawn».

Estará o PPM adaptado à realidade da nova rádio?

A rádio do futuro terá ainda mais mobilidade, será mais portátil mas mais difusa. Não haverá um aparelho chamado "rádio" e as (novas) empresas de rádio serão fornecedores de conteúdos audio (não apenas).

Neste cenário em que o webcasting terá prevalência, em que a rádio chegará por todos os lados e não apenas pelo ar - como agora - será que o PPM (e os aparelhos de medição electrónica passiva em geral) está adaptado às novas circunstâncias? Ou será que o investimento brutal que será preciso fazer, por exemplo nos EUA, se mostrará desajustado alguns anos depois (um pouco como o DAB?)?

A questão é que, como mostra este texto, «As we saw forty years ago, a period of change for the medium can precipitate a change in measurement» (North, Nick e van Meurs, Lex,  «Radio Zapping», ESOMAR/ARF WAM, June 2004). Nesse sentido, a medição electrónica, tal como a conhecemos agora, não servirá para a nova realidade que se avizinha...

A pré-história da medição electrónica, 40 anos antes

«The minute-by-minute, mechanical measurement of radio audiences was first introduced in 1942. AC Nielsen’s Audimeter registered each movement of the radio tuning dial with the scratch of a stylus on a roll of paper tape, storing the information in a cartridge, which at the end of each survey period was mailed back to the company for analysis. From 1950 until 1963, the Audimeter-based Nielsen Radio Index served the US radio industry as its official currency. Technological change and legislative action brought about its demise:

The sales of new, portable transistor radios starting in the late 1950s and the advent of stereo FM broadcasting in 1963, adding to the already growing number of channels that could be received, undermined the practicability of the system;

In the same year, the radio ratings industry was in the dock, with a Congressional Hearing concluding that, based as they were on statistical estimates, all ratings were “inherently imperfect”.

Nielsen abandoned minute-by-minute measurement of radio, and the industry moved to a diary-based survey of radio audiences – an established methodology which was not without criticism. As one contemporary commentator noted in 1954: “…the placing of diaries can be a haphazard method scientifically, since many people refuse to accept them, which could throw an entire sample out of kilter. Also, there is a tendency to neglect filling out the diary until the last day of the week. Here, too, memory is unreliable and people will put down anything that comes into their heads—including, occasionally, shows which haven’t been on the air for years... As comedian Herb Shriner put it, “If you stop a woman leaving a supermarket and ask her to tell you everything she just bought, she won’t be able to. So how can she be expected to remember what she listened to a week ago?” Bill Davidson, “Who Knows Who’s on Top,” Collier’s, 29 October 1954.»

North, Nick e van Meurs, Lex,  «Radio Zapping», ESOMAR/ARF WAM, June 2004.

(obrigado Jorge)

Clear Channel avança com o seu processo de medição

Desenvolvimentos do processo iniciado pela Clear channel para criar um sistema autónomo de medição de audiências, contra a hegemonia do PPM:

«Three advance for radio ratings
The Next-Generation Electronics Ratings Evaluation Team - - the new name for the multi-company team evaluating responses to Clear Channel’s RFP - - has selected three finalists for a new, electronic radio ratings system. MediaAudit/Ipsos, Arbitron (PPM) and Mediamark Research are being invited to provide more details later this month, with some then to be invited to proceed to a live test stage - - with commercial implementation of a new radio ratings system still targeted before the end of this year. (...) "The evaluation team was impressed with the ingenuity and proven track record of several of the finalists and is particularly interested in the cell phone as a measurement device," said Clear Channel Radio Sr. VP of Research Jess Hanson. RBR observation: Not really any surprises here. The three finalists were the ones known last year to already have a working portable measurement device, so no one has made it through to the finals with some new wizbang proposal that no one had seen before. Hanson’s comment about the evaluation team’s interest in using cell phones is good news for MediaAudit/Ipsos, which is known to be using such a device, but potentially bad for Arbitron, which sees problems with using cell phones and has resisted incorporating PPM into cell phones. (...) The third finalist, Mediamark Research, continues to decline to make any public comment about its entry. Its proposed system is believed to use the Eurisko Media Monitor, which was developed by a related company.»

fonte: RBR news, Volume 23, Issue 49, Jim Carnegie, Friday Morning March 10th, 2006

Sobre o uso do telemóvel como medidor/IPSOS:«The Media Audit reports that its Smart Cell Phone meter will measure broadcast audiences via watermarking (encoding) and audio matching. Watermarking involves encoding radio and television signals with an inaudible or invisible encrypted watermark code. Encoding involves the cooperation of broadcasters to insert a code into their transmissions. The watermark code is detected by the Smart Phone meter and provides the measurement of the stations that each respondent is listening to and/or viewing. The encrypted data is stored and transmitted back to the data
center on a daily basis.»

As vantagens que o PPM trará à medição electrónica

 PPM will provide never-before-available insight into station switching patterns and loyalty. For example, 58% of P1s switch their P1 station at least once over an eight-week period.

* The diary-based methodology and PPM agree that P1 listening drives the vast majority of the AQH rating, even with the much larger cume shown in the PPM.

* The longitudinal nature of PPM will provide for more stable ratings on a period-by-period basis, leading to more accurate data to assess the impact of programming and marketing initiatives.

Among issues before the industry:

* Understanding the effect and impact on measurement error of smaller, longitudinal samples of consumers versus cross-sectional diarykeepers.

* How and if the industry will benchmark or adjust for the ratings differences created from the switch to PPM, where consumers are listening to more stations but less to any given station.

(excerto da notícia: «White Paper Heralds PPM Potential», Billboard Radio Monitor,March 01, 2006, By Chuck Taylor)

Nielsen desiste de levar o PPM para a televisão (EUA)

«Arbitron’s Portable People Meter (PPM) is going to be a radio only ratings system. Nielsen Media Research has decided not to exercise its option for a joint venture with Arbitron to deploy PPM commercially across the US. Nielsen says it may license PPM for use in measuring out-of-home viewing, but is evaluating other options for measuring in-home viewing. (...) "We recognize the appeal of a portable, single source measurement tool. While it may offer considerable benefits for radio research, we believe that a one-size-fits-all measurement system is not the approach for a currency in today’s complex television markets," said Nielsen Media Research CEO Susan Whiting. Nielsen said yesterday it had concerns about sample quality, including fault rates, said PPM’s definition of "audience" resulted in "large and still unexplained increases in television viewership," which it attributed to PPM being designed to measure radio rather than TV, said that costs would be high and it appeared that TV would be subsidizing radio measurement, and questioned how many TV companies really support moving to PPM measurement. At Arbitron, CEO Steve Morris said his company will focus on its "radio only" option for rolling out PPM. Without having Nielsen as a partner, he noted that Arbitron will have "complete flexibility" for where and how to roll out PPM - - not mentioning that it will mean that the cost will be higher for radio broadcasters. Morris will hold a conference call with Wall Street analysts this morning to discuss the financial ramifications of the Nielsen decision to walk away. Just two days from now (3/3), Clear Channel is due to announce whether it and the radio groups which have joined in evaluating proposals submitted under its RFP on passive electronic radio audience measurement have selected PPM or one of its competitors as the best system to serve the US radio industry.»
(fonte: «Nielsen walks; PPM to be radio only»)

O presidente da Arbitron: «“I’m obviously disappointed since we and they [Nielsen] have invested a lot of time and effort in looking for a way to make this work,”(...) “Looking forward,” Morris added, “we now feel we’re free to focus on radio’s needs without having to negotiate trade-offs to accommodate television requirements.”» (fonte Billboard Radio Monitor, Arbitron's Morris: 'We're Disappointed', March 02, 2006, By Mike Boyle)

 

Sobre a Eurisko, o EMM e o PPM

«(...) Eurisko Media Monitor (EMM) is adaptable for any customers needs. “It is not a watch, pen, necklace or mobile phone but it could be any of these.”

Electronic measurement as currently developed relies on two technical methods; watermarking and sound matching. Arbitron, developer of the Personal People Meter (PPM), uses a watermarking technique that embeds identifying codes in a stations transmitted signal. The Swiss-developed RadioControl device uses sound matching.  Eurisko settled on sound matching. Requiring stations to embed codes in their signals was considered “impractical,” according to Mezzasalma. “It gives power to the stations to discontinue the service,” he said. (...) According to Mezzasalma, who has carefully studied watermarking methods, the PPM requires five minutes to identify a signal. “Five minutes is a lot of time,” he said. “Television clients would find this unacceptable.”

Radio measurement is not uniformly organized throughout Europe. Where joint industry committees are in place, broadcasters – public and private – and the ad industry, decide what is measured and how it is done. More common are individual and competitive market research companies who determine methods and sell the service to broadcasters and media buyers. GfK and TNS Gallup provide media measurement services in several countries. GfK, the licensed provider of Radiocontrol, offers its service in the UK and has conducted tests for broadcaster groups in other countries.

(fonte: Italian Company Enters Radio Measurement Competition, Follow the Media, Michael Hedges February 1, 2005)

 

Arbitron cerca a Clear Channel e impõe o PPM

Depois da Clear Channel (o maior grupo de rádios dos EUA) ter dito que não concordava com os prazos de desenvolvimento do PPM, e ter iniciado um processo paralelo e concorrente à implantação do PPM, a Arbitron reage. Mantém o mesmo calendário, responde à proposta da Clear Channel e começa a mostrar a sua força: primeiro com múltiplas agências de puclicidade e agora com os concorrentes da Clear Channel. "Arbitron announced Spanish Broadcasting System has entered into a multi-year, multi-market agreement for Portable People Meter audience measurement services when deployed in its New York, Los Angeles, Chicago, San Francisco and Miami markets (...) This is the second announcement of a radio broadcaster signature on a contract for PPM ratings services (Beasley Broadcasting signed on 1/31). Arbitron has been working to secure a critical mass of stations and agencies to allow it to go forward with PPM". (Radio Business Report, «SBS signs for PPM», Volume 23, Issue 4, Monday Morning February 27th, 2006)

Telemóvel da IPSOS readmitido nos testes da RAJAR

Desenvolvimentos sobre o negócio da medição electronica de audiencias, nomeadamente na GB e em concreto sobre a exclusão do sistema da Mediawatch nos testes da RAJAR:

«After the GfK RadioControl watch was kicked out of the exhaustive test (“One of the devices clearly did not work,” said an anonymous observer close to the RAJAR board) RAJAR held up most of the scheduled trials so Ipsos could get it’s new gizmo together, a solid year after the others. Better to have three to choose from than only two.

The Ipsos gadget is based in a cellphone. The advantage being that compliance is always a problem and everybody carries a cellphone. And the Ipsos device will measure every platform – radio, TV, cable, internet – and have a GPS locator so maps can be drawn showing exposure to billboards and shopping centers. Does anybody want to see the privacy policy?

Certainly not ad agencies who love all data: good, bad or ugly. And since they make the broadcasters pay for it all, why not demand more, more, more?(...)

Arbitron’s Brad Bedford, in a telephone conversation last summer about the Ipsos cellphone, asked the very simple question: “Is somebody going to carry two cellphones, one with your address book and one to measure radio?”

Eurisko, now owned by GfK NOP, hasn’t entered the US battle. Typically cheerful VP Andrea Mezzasalma said “We can put the Media Monitor in anything; cellphone, pager, ballpoint pen.”

(fonte: Follow the Media, Ipsos Cellphone Radio Measuring Thing Maybe Included in RAJAR Tests, Michael Hedges February 24, 2006)

A grande vantagem deste sistema é que incorpora a ideia do PPM (uma sinal incorporado na emissão) com uma espécie de medidor de todos os sinais audio que se escutarem: "The Media Audit and Ipsos have joined forces to market a new passive media audience measurement system in the US. The two companies came together in response to the radio industry's interest in an alternative ratings service that will use  technology to monitor radio listening and include new ways to sell radio's advertising strengths...

"The Media Audit / Ipsos new audience measurement system includes two forms of monitoring software—an encoded watermark embedded in the broadcaster's audio signal and an audio matching technology that will measure broadcast signals of those stations that are not encoded. "The Smart Cell Phone, via the Ipsos software, monitors the individual's exposure to radio, other electronic media, the internet and out-of-home. In addition it has the facility to track retail shopping patterns via a GPS system...

"The Media Audit will initiate a field test of the Ipsos watermark software in mid-year 2006 in the U.S."» (fonte: http://www.kurthanson.com/archive/news/022406/index.asp)

Arbitron vai integrar ouvintes só com telemóvel

A notícia da Billboard radio Monitor diz que a Aribtron vai passar a angariar clientes para os seus "diários" que tenham apenas telemóvel e não telefone da rede fixa.

Até agora os "voluntários" que preenchem os «diários» que suportam as audiências de rádio norte-americana são contactados via telefone fixo. Mas, diz a notícia, cresce o número de norte-americanos que têm apenas telemóvel: «For the first time ever, the ratings company will recruit diarykeepers by calling cell phones, starting in 2008. The development is significant because an increasing percentage of Americans rely exclusively on cell phones and have not been included in Arbitron ratings surveys».

A questão é outra: se as audiencias vão passar a ser medidas electronicamente, pelo PPM, esta medida é de curto-prazo. Claro que até o PPM estar implantado em todo o território norte-americano vão ser necessários vários anos, mas o sistema dos «diários» está condenado.

Uma voz desalinhada com o PPM

«“It’s a process that’s evolving,” Feinblatt tells Monitor. “Do I personally think it’s a better measurement? I think it probably is, but we still have some questions about it. We have some questions about cost and things like that . . . there are still some things that need to be vetted out and it’s an expensive proposition. We’re not going to rush to judgement.”»

Entretanto a Arbitron continua a tentar conseguir a acreditação do PPM: "As part of Arbitron's ongoing efforts to achieve Media Rating Council (MRC) accreditation of the Portable People Meter (PPM), another phase of the independent audit of the PPM ratings system has been delivered to the Council. The audit was designed to authenticate and illuminate the procedures used in the PPM ratings system for radio and television. Any audience measurement service that desires accreditation is required to disclose to the MRC membership all of the methodological aspects of their service; meet MRC Minimum Standards For Media Rating Research; and submit to MRC designed audits. The membership then evaluates these audits and the Board grants accreditation if deemed warranted."

Agências de publicidade querem PPM

"Media buyers are ready for radio to embrace electronic measurement. And while a few early bumps are to be expected, in the end radio will benefit from it. That was the word from a panel of advertising professionals at the Radio Advertising Bureau’s RAB 2006 which wraps up here today (Feb. 3)." ("RAB Day Three: Buyers Ready For Electronic Measurement", Billboard Radio Monitor, Feb. 03, 2006, By Ken Tucker) (via Obercom)
 

Mais uma voz contra a medição de audiências por entrevista

«El presidente de Onda Cero, Javier González Ferrari, quiere actualizar la forma de hacer la muestra del Estudio General de Medios (EGM) y ha vuelto a pedirlo en público. A su juicio, el sistema actual "es una antigualla" y su fiabilidad "relativa". González Ferrari, que intervino en una convención de directores de emisoras de la cadena en Segovia, afirmó en declaraciones a los periodistas que "seguir haciendo la muestra basada en el recuerdo, con los adelantos tecnológicos que hay actualmente, me parece una antigualla".» "Ferrari vuelve a insistir en que la forma de hacer el EGM es 'una antigualla' y hay que actualizarla", El Mundo, Actualizado viernes 03/02/2006 16:55, EFE (via Clube de Jornalistas)

O método RAJAR (GB)

(e os problemas na medição de audiência)

«Understandably, measuring radio audiences is complicated: radio can be listened to virtually anywhere and there are literally hundreds of station areas to survey. The cost to the radio industry for this service is almost £4 million a year. RAJAR produce listening figures every three months based on the the response from 3,000 selected respondents who each compile a seven-day diary of their listening habits. While this may seem a time-consuming and old-fashioned method of measuring audiences, because radio is listened to in a variety of locations it is still felt to be the most reliable. Several types of radio-meters are being developed, but because they require respondents to carry or wear the meter at all times, their effectiveness is still in doubt". (Fleming, 2002: 15) 

A importância de haver apenas um sistema de medição de audiências (GB)

«(...) BBC and the Commercial Radio Companies Association (CRCA) set up a radio industry research company - RAJAR Ltd - in 1992 which they jointly own. Prior to this, audience data were collected by two separate services: the BBC Daily Survey which monitored BBC radio, and the Joint Industry Committee for Radio Audience Research (JICRAR) for commercial stations. The problem with this was that different methodologies and the fact the figures were not independently produced cast doubt on their accuracy. As RAJAR (Radio Joint Audience Research) points out: "The creation of RAJAR has greatly improved overall confidence in radio as a medium over the years since 1992, principally because it provides a single accepted measure of radio listening"(www.rajar.co.uk).

(Fleming, 2002: 15) 

Críticas ao método da Arbitron

(e se a Arbitron, com tudo o que ela significa, tem estas falhas...)

Citações de Eric Norberg, ibidem, pág. 133-136

1) "El principal servicio estadístico es Arbitran, que utiliza cuestionarios distribuídos por correo, auto-administrados, de siete días, para recoger información de escucha radiofónica (...). Arbitron saca una muestra de la guía telef6nica para mandar los cuestionarios. En mi opinión, este proceder compromete aún más los datos";

2) "Como Arbitron comienza por una muestra de teléfonos de la guía se excluyen los no registrados en ella";

3) "(...) es que no pueden garantizar que van a obtener el mismo grado de cooperación de la muestra registada que de la no registrada. En cierto modo, entonces, las dos muestras no son equivalentes, y una puede distorsionar los resultados de la otra";

4) "(...) quienes voluntariamente no figuran en la guía - los que pagan una cantidad adicional para que no se les incluya en la guía telefónica- no suelen colaborar cuando se les pide el nombre y la dirección, ya que el entrevistador obviamente no sabe quiénes son y ha marcado ese número al azar. ¿Darían a cualquiera esa información? Pagan por su intimidad. Si al entrevistador no le dicen su nombre y dirección no pueden recibir el cuestionario y no se les incluirá en el informe";

5) "(...) pienso que el tamaño eficaz de la muestra, en el caso de los estudios de Arbitron, estaría mejor expresado por el número de «domicilios estudiados» y no por el número de cuestionarios del estudio, - lo cual representa un número sustancialmente menor. Creo que, para eliminar este efecto, debería contestar solamente una persona por domicilio".

6) "(...) cuando quienes participan en el estudio saben de antemano que serán estudiados, (como cuando reciben un cuestionario por anticipado) este conocimiento previo puede cambiar su conducta. Como Arbitran es la única empresa de estudios que ha proporcionado hasta ahora este conocimiento previo a la muestra con mucha antelación al esludio, es especialmente vulnerable a este inconveniente";

7)"(...) como Arbitron es la única empresa de estudios que debe saber el nombre y dirección de aquellos a quienes llama (para mandarles los cuestionarios) Arbitron es especialmente vulnerable al tema crítico de la intimidad";

8) "En todos los informes de Arbitron está comprobado que sólo una parte de quienes reciben los cuestionarios los devuelven";

"En resumen, todas las empresas de estudios fracasan en la obtención de una muestra verdaderamente representativa de la población. Sin embargo, la principal, Arbitron, con su sistema de etapas múltiples en la cooperación de los encuestados (contacto telefónico inicial, obtención de colaboración con los envíos postales, posterior necesidad de más colaboración para conseguir la devolución de los cuestionarios) y con las dificultades que significa el uso de encuestados múltiples en el mismo domicilio es, en mi opinión, la menos precisa de todas".