Starcom, one of the first media buying agencies to buy a new stream of minute-by-minute ratings from Nielsen Media Research, made an upfront deal last week with The Weather Channel based on the new data.

The deal covers eight Starcom clients and guarantees that if viewing levels for those clients’ ads fall below specified levels, they will get make-good ads, the agency said. The Weather Channel was the first network to buy Nielsen’s minute-by-minute ratings.

The minute-by-minute information is different from the average commercial ratings data most networks are talking about using during next year’s upfront, where the bulk of prime-time ads are sold. Both sets of ratings data are meant to give advertisers a better account of how many people are watching their commercials. In the past, Nielsen’s ratings have measured only audiences for the programs in which commercials appear.

The minute-by-minute ratings that The Weather Channel and Starcom will use focus on individual minutes during a program when a particular commercial airs. The average commercial minutes data most other networks are considering measure average audiences for all of the commercial minutes within a particular program.

The Weather Channel has experimented with other ways to assure advertisers that their investments in commercials are creating a return on investment. Last year the cable channel struck a deal with MediaVest based on viewers’ ad recall. In that agreement, the agency and the network did research comparing recall of commercials on The Weather Channel with scores on a broad range of cable channels.