How is the TOP 40 actually calculated?

[dod]

I have never really understood how TOP 40 charts are actually calculated.
With the introduction of iTunes and other legal music download sites, I was wondering if these are now taken into account.
If anyone can enlighten me, I would appreciate it.

[paulfryer]

The Official Top 40 Singles chart as used by the BBC now uses CD sales and legal paid downloads from iTunes, Napster and other companies (other legal download sites, record labels and high street retaliers etc). The download information was merged with CD sales in spring 2004 (when Tony Christie was at no1 with "Amarillo"). In the very early days of the 1950s & 1960s music magazines compiled their own charts the (NME is generally considered as "official" and is used as the chart archive for the 1950s and The Record Retailer chart for the 1960 & 1970s). When the 1st chart came out in November 1952, the editor of the NME phoned around 12 London stores to see what had sold, this simple method was the norm in the early days, but the sample of stores increased. The Record Retailer chart became independently audited in 1963 and from 1969 BMRB (British Market Research Beuraux) compiled the chart for the BBC and Record Retailer. The sample of retail outlets grew over the years to around 500 in the 1980s. Radio 1 used to announce the new top40 on a Tuesday and air that chart on the following Sunday. This was because before the advent of computer technology it took several days for the chart to be compiled. So when the full Sunday chart aired it was already a week out of date. From 1987 with the help of computers Gallup who then compiled the official chart started publishing the chart on a Sunday after previous weeks sales were taken into account. This is still done today: the chart week runs from 00:00 on Sunday to 23:59 on Saturday for release the following day. Millward Brown started compiling the chart in 1994 after winning the rights from Gallup and the sample of stores increased to 1000 and over. Around the same period CIN (Chart Information Network) owned the rights to the Official charts. CIN has now been renamed "The Official Charts Company" to reflect its core business. A note worth mentioning is that the downloads eligible for inclusion into the top40 have to be released as CD singles as well. And the CD single has to comply with the chart rules. The chart rules are complex but generally singles are limited to length, number of tracks and the prohibition of promotional items such as free exclusive extra CDs, dvds etc. That is not to say that they cannot be released for sale, but rather they will not qualify for the singles chart. It is possible for record companies / artists to adhere to these rules and still get into the top 40 by downloads alone. In the summer The Gorillaz released around 250 copies each week of Feel Good Inc into the shops. Now 250 would only get a CD single to about 160 in the chart (a top200 is published, but very few people see more than the top75 [2000-2500 is the usual to enter the Top40]), but as it was still in the chart then the downloads could be taken into account. For a few weeks Feel Good Inc was in the lower half of the Top40 on downloads alone before the official mass release of the single helped to push it into the top 10. As far as I know there is no co-efficient etc, every download is worth the same as a CD single. The BBC official top40 is based on eligible sales and downloads only. The sample of sales now takes into account 99% of all singles cd sales (less for albums), so major high street music stores, supermarkets and distributors to independents will have sales tracked. The only sales not taken into account are things like music clubs & mail order. As these outlets generally sell albums rather than singles this is perhaps why only 80%-85% of album sales are tracked for the official album charts.
There are other charts worth mentioning. MRIB the research company has been compiling a singles chart since 1985. This was done for use on the local commercial radio network. Because the Gallup chart was 10 days behind so to speak on Radio 1, MRIB complied a chart with sales up to Thursday, for use on the Sunday. Although not official, this chart was aired at the same time as the BBC Radio 1 chart and was essentially 1 week ahead. Of course that changed in 1987 when Gallup and Radio 1 started to air the top40 less than 24 hours after sales had closed. The commercial network chart was the "The Network Chart" and was hosted by former Radio 1 dj David 'Kid' Jensen from Capital Radio in London. In late 1993 Neil 'Doctor' Fox replaced Jensen and the chart was then sponsored by Pepsi and given a fresh youthful sound. In 1994 this chart overtook the BBC top40 in audience figures which hastened the departure of Bruno Brookes in 1995. Also in 1995 the Radio 1 chart got a whole new sound similar to The Pepsi Chart (they used the same jingle companies) and was now hosted regularly by Mark Goodier. The "Pepsi Network Chart Show" as it was called in its infancy used the official top10 as Radio1 with 11-40 being based on sales and radio airplay. I remember in 1995 Simply Red's - Fairground was at number 11 for a while before the single was released. This was simply because it had so much airplay it was pushed up to number 11, but could not enter to top 10 as the official top10 was only based on sales. This chart then became known as just "The Pepsi Chart" and Neil Fox (Pop Idol Judge) retired in early 2004. It is now sponsored by Woolworths, is called "Hit 40 UK" and presented by Galaxy 105 Yorkshire breakfast dj Simon Hirst. It is still presented from London though, so that means a bit of travelling for the Barnsley dj.
Another lesser known radio top40 is the "Smash Hits Chart". Emap radio a very large group within commercial radio, broke away from the Pepsi chart in January 2003 when the Pepsi contract ended and it became Hit 40 UK. The chart is hosted by Mark Goodier who retired from the BBC Radio 1 chart in November 2002. This chart is aired on all the Emap FM stations (except Magic 105.4 in London), which includes Kiss FM in London and nearly all local county size stations north of Liverpool/Manchester & Sheffield. It is also heard on other smaller scale radio station across the UK. This chart is supposed to be coming to an end soon as Emap is going to retake the Hit 40 UK show. So just briefly this chart is compiled by sales from MRIB (who still compile chart data like 20 years ago), radio airplay and video request data from the Emap digital tv channels The Box, Smash Hits TV & The Hits. In this sense it is the most representative chart around (although radio & tv execs decide what is on a playlist).
I hope this helps, even if I have gone off track slightly.

*As of March 2006 - The Official UK Charts Company will be allowing the inclusion of downloads into the chart 1 week before physical release. Previously such circumstances would have meant the track only being in the download chart until the physical release became available the following week.*
This policy was intoduced as a compromise betwen the music industry and the music retailers. If downloads were included into the main top40 more than 1 week prior to physical release, this would have meant empty spaces on store shelves (ie numbers 13,17,22,25,29,34,37,39 in the main top40 on downloads alone with no physical equivalent).

[Mira]

That pretty much answers it. In the US, it's the same, a collaboration of R&R( radio and records industry mag- which calucates rotation in diff markets and radio formats and audience size), downloads, radio rotation, and Soundscan (actual retail purchases). Lots of calucators going off and coming up with as much of an accurate number as they can. Neilsonratings.com as well.

[Mira]

Napster, iTunes and other download stores having reporting structures that vary. It is know that Apple has fudged their numbers, because they include QA downloads in their final numbers, which should not be counted as purchased music. Whatever. They are Apple. They can do what ever they want and they know it.