A decision maker (or decider) is a person who has the responsibility for making certain decisions. The decision made is usually a result of information provided and the decision maker’s preferences, values and beliefs. A person making a decision must usually be committed to it personally and may be required to persuade others of its merits. The term decision maker may also be applied to those responsible for the final purchase decisions within a decision-making unit (DMU).
Making a decision usually involves the decision maker having to choose from a number of possible solutions, each of which may or may not guarantee the required outcome. The art of successful decision making usually requires an understanding of the consequences of each available choice. It is usually a process that is either reasoned or intuitive (gut feeling), or a combination of the two. It is possible to make a decision without having a real idea of what the outcome is likely to be – but this may be no better than a blind guess.
Decision making usually involves choosing from two or more alternatives. However, even when there is only one course of action available, a decision is still possible: either to proceed or not to proceed with that particular option.
 Staged decision criteria
Making a decision can involve a number of decision criteria, usually as part of a staged process. An example is the way consumers purchase things, which typically involves:
- Recognising the need.
- Researching and identifying what is available.
- Evaluating all possible alternatives.
- Choosing from the alternatives.
- Making the purchase.
In making such decisions, it is usually recommended that the decision maker should try to maximise the expected utility (or value) that might arise from their choice. A rational being appointing a builder to re-roof a house will necessarily procure what they believe to be the best value work to ensure a functional, durable roof. This decision is often expressed in monetary terms: it is unlikely that the lowest-priced roofing quote will yield the best outcome. Therefore, price becomes one of the decision criteria.
Purchasing in business-to-business scenarios is usually part of a complex buying network. The more strategic purchases tend to be made by staff at the more senior levels. Major decisions may be made by the chief executive officer (CEO), technical director, purchasing director or the procurement manager (buyer); for less significant purchase decisions, the decider might be a junior buyer or member of staff in charge of making purchases at that level. Being given responsibility to make a decision or type of decision is known as 'delegated authority'.
 Problems for the decision maker
The decision maker may face one or more of the following problems:
- Not enough information.
- Urgent deadlines,
- Too much information – not seeing the wood for the trees.
- Limited resources.
- Too many people involved – this may result in decision by committee.
- Vested interests.
- Emotional attachment – prevents objective decisions.
- Indifference to the outcome.
- Conflicting requirements.
- Building Information Modelling.
- Choosing a builder.
- Choosing tenders to bid for.
- Decision making unit DMU.
- Delegated authority.
- Employer's information requirements.
- Integrated project team.
- Integrated supply team.
- Investment decision maker for building design and construction
- Liability for building design
- Selection criteria.
- Senior responsible owner.