Hi, I'm trying to set up a stimulus that would be a lot like watching regular TV...including commercial breaks. I have a clip of American Idol that I have edited into 3 sections to allow for 3 commercial breaks (don't worry, our Ps will get plenty of extra credit for being forced to watch American Idol!). I'd like the commercials to be chosen randomly without replacement from two pools of ads I have (target ads and filler ads). Each commerical break would have 3 commercials...2 of which were fillers and one a target ad.

In other words, Ps would watch part one of the American Idol clip and then see 3 commercials. Two of these would be fillers and one would be a target commercial. Then they'd watch part two of the American Idol clip and 3 more commercials. These would also be 2 fillers and one target, but could not be any of the commercials already viewed. Then part 3 of American Idol followed by the final 3 commercials...also 3 new commercials. So they'd watch 9 commericals in all, 6 of which were fillers and 3 target, and no commercial would be seen more than once.

Any ideas? Thanks so much for your help!
Missie