TVision study: Longer television ads do not always justify higher cost of inventory

Longer television spots do not always justify higher budgets in terms of the reach and attention they generate when compared with shorter TV ads, a study by measurement company TVision suggests.

An established rule of thumb for buying television advertising is that prices increase in direct proportion with the length of a spot.

In practice, that means a 60-second ad often requires twice the budget of a 30-second commercial. And a 15-second ad,...