Cooper suggests that successful product development needs to operate some form of structured, staging process. It includes filter:

a$.$ ideas to preliminary investigation$-$products to business opportunities$-$products to product$/$process development$-$projects to limited lunch$-$products to international market.

b$.$ ideas to preliminary investigation$-$projects to business opportunities$-$projects to product$/$process development$-$products to limited lunch$-$products to international market.

c$.$ ideas to preliminary investigation$-$products to business opportunities$-$products to product$/$process development$-$products to limited lunch$-$products to international market.

d$.$ ideas to preliminary investigation$-$projects to business opportunities$-$projects to product$/$process development$-$projects to limited lunch$-$projects to international market.