Change something by a percentage.

Predict what will happen if you change it by some other percentage, and so calculate the optimum.

Make a concrete comparison with a competing or alternative product.

Create a written specification

Create a written specification which belongs to the organisation. This will survive staff turnover, give continuity of features and core qualities, and so help to create and maintain strong brand values.

Avoid mistakes caused by subjective decision-making, last-minute judgement calls, and especially decisions made in meetings. Meetings are very poor at processing information, and highly social in their behaviour. Most meetings are chaired by people who have the 'big picture' but are not expert in the technical details of a design, and who are unlikely to represent their customers in knowledge, intelligence or even size. Hard data is the way to make sure that decisions are of high quality.

See also: Techniques