following table provides principal sources of information for main media audience research in English speaking markets. Notes: * Also see Nielsen Media, for Trends in Canadian TV Viewing ** English is one of the three official languages spoken in Malaysia. Print and broadcast media are normally segmented into language first and demographics second. *** There is so single, official currency for measuring TV audiences in Malaysia. Currently two competing companies provide data, using different methodologies (Nielsen Media and Kantar Media) **** Think TV is a consortium of commercial TV networks that oversees the TV ratings process Media buying While it is certainly possible for advertisers to purchase advertising spots by dealing directly with media owners (e.g. newspapers, magazines or broadcast networks), in practice most media buying is purchased as part of broader negotiations. Prices depend on the advertiser's prior relationship with the network, the volume of inventory being purchased, the timing of the booking and whether the advertiser is using cross-media promotions such as product placements. Advertising spots purchased closer to air-time tend to be more expensive. Many advertisers opt to centralise their media buying through large media agencies such as Zenith or Optimedia. These large media agencies are able to exert market power through volume purchasing by buying up space for an entire year. Media agencies benefit advertisers by providing advertising units at lower rates and also through the provision of added value services such as media planning services. Buying advertising spots on national TV is very expensive. Given that most media outlets use dynamic pricing, rates vary from day to day, creating difficulties locating indicative rates. However, from time to time, trade magazines publish adrates which may be used as a general guide. The following table provides indicative advertising rates for selected popular programs on American national television networks, broadcast during prime time viewing hours. Notes: * Rates for programs such as American Idol increase as the program moves closer to finals ** Rates for Mon-Fri programs such as Jay Leno vary depending on the day of the week and the expected audience size Pulling it all together: Media tactics and the media schedule A media schedule is a program or plan that "identifies the media channels used in an advertising campaign, and specifies insertion or broadcast dates, positions, and duration of the messages". Broadly, there are four basic approaches to scheduling: Blitzing: one concentrated burst of intense