WPP Group market research firm Millward Brown will begin offering a web advertising copy-testing service - DigitalLink - to agencies, similar to services it offers for TV, print, outdoor and radio ad campaigns, reports AdWeek. The first collaboration between Millward Brown and Dynamic Logic, the online advertising brand research firm it bought in June, DigitalLink will test creative executions via user surveys to determine whether they achieve campaign branding objectives. The service will be tested starting November 1, and launched soon thereafter.