The question now is, how attractive and distinctive really are the new product or service concepts? After the brainstorming session and concept development workshop, this is a justifiable question. I would advise you, after the first feeling of euphoria, immediately to reflect on the developed concepts and if necessary improve them or put them in the freezer if the market research shows that you have completely missed the boat, because that can also happen. This stage lasts three weeks: a short period, under great time pressure, to keep the tempo in the FORTH process. At the end of this stage – Test Ideas – the ideation team can plunge themselves into the making of mini new business cases for the best three to five product concepts.