When making decisions, project managers should heed the following caveats.
Recognize that enough facts and data will never be available. Project managers will never reach a point of completeness, regardless of how much a perfectionist they might be. They can "drill down" into databases, interview a host of people, and review piles of documentation and still feel uncomfortable with the degree of facts and data. Besides, a point of diminishing returns may arise when pursuing more facts and data. It will also add to the angst of facing ambiguity, even intensify the feelings. Edward De Bono agrees and notes that it is virtually impossible to obtain complete details. In fact, he adds, a person can seek so much detail that it may decrease clarity. 
Acknowledge the role of emotion as well as logic in decision making. Decisions are a human endeavor. In an effort to think and appear objective, many project managers strive to be objective but ignore the emotional side. However, their emotions ” from anger to fear ” will be meshed with their logic; it is part of the human condition. This emotion will be reflected largely in their response to the circumstances. Emotions will determine not only what they consider facts and data, but also what they select and process. It will also influence their selected response to a situation. Our moods powerfully affect our thinking in general and decision making in particular. Hence, a good mood will encourage us to do something risky while a negative mood leads us to be cautious. 
Decisions often involve a choice of values, reflecting a subjective , not objective, exercise. What a person deems important versus unimportant often reflects their preferences and biases built up over the years either through learning or experience. When project managers are in a decision-making position such influences affect, either overtly or subtly, the choices made. They will affect the ability to define the issue or problem, identify alternatives, select the best solution, and implement it. Some overt influences include vocation and experience. Some subtle influences include attitude, limited knowledge, education, and risk acceptance level.
All decisions have consequences. Project managers do not operate in a void. By virtue of their position, they influence just about everything on a project, as they are essentially linchpins. They are in the locus of decision making. It is important, therefore, that project managers realize the impact of their decisions.
These impacts of decisions can be classified in several ways.
Impacts can be short or long term. A short-term impact affects activities early on, e.g., during the current phase of a project's life cycle. A long- term impact might be felt much later on.
Impacts can be explicit or implicit. An explicit impact is easily tangible , e.g., reducing rework resulting from the efforts of a specific task. An implicit impact is very hard to detect, e.g., a decrease in morale or esprit de corps. Implicit knowledge may be even more meaningful despite not being quantifiable.
Impacts can be positive or negative. A positive impact furthers progress, e.g., a decision to adopt a new process. A negative impact retards progress, e.g., a decision to change scope without coordinating with people.
Naturally, a decision can be a combination of all three categories. For example, the impact of a decision can be explicit and positive, like a reward for performing a task well. Or, it can be long-term, implicit, and negative, like a decision not to perform a process at the time because it seemed unimportant but later causes rework and schedule delay.
Decisions are neither "right" nor "wrong" per se. Many project managers want to "make the right decision." The reality is that there is no right decision and that many decisions may be right or wrong only from the perspective of the frame of reference or mental model of the decision maker. This desire for being right and correct often leads to premature decision making because people jump to a conclusion. Consequently, project managers are often at constant war with their circumstances by imposing decisions and then "selling and marketing" them. In reality, many decisions do work that way, each with its unique consequences. What project managers should strive for is to identify options to address and selecting the best, not the right, one.
Decisions must consider the context of an environment. While seemingly straightforward, this is often ignored. Many project managers make decisions as if inside some egg, immune from the outside world, e.g., isolating themselves from daily project activities. Effective project managers act like open systems, however, attuned to activities and events whether internal or external. To lead effectively, they must factor such considerations into their decisions.
Decisions are rarely, if ever, isolated acts by a project manager. Yet, many project managers make decisions exactly that way. They unilaterally make decisions, ignore input, or do not consult with others. They fall into an "Ivory Tower" trap and issue impractical and unenforceable declarations on large projects. The reality is that decisions require both information about circumstance and notification about the need for decision making. Still, many project managers act unilaterally only to find their decisions often flawed, failing to achieve effectiveness, and creating constant tension. They need to consider the scale of consultation and participation in decision making. Of course, project managers need not consult every stakeholder on every decision. It is a matter of circumstance. As Thomas Gordon notes: Everyone on a team needs to be involved and then be available when needed. 
Sometimes not making a decision is the best decision, if intentional. Some project managers feel they have to make a decision. However, occasions arise that necessitate making a decision under different circumstances or at another time. Many project managers rush to judgment even without defining exactly the issue or problem under consideration or the relevancy of the facts and data. Instead, they exercise a "fire, ready, aim" rather than a "ready, aim, fire" attitude.
Sometimes this approach will work but project managers need to recognize when it is best to "shoot from the hip" rather than "shoot from the head" and vice versa. When the former, it is always wise to consult with someone, if warranted, to avoid creating a bigger problem or issue than the original one.
Decisions often deal with problems or issues of gray rather than black or white. This point is related to the last one. Many project managers simplify for ease of decision making. Simplification may make decision making easier, but it may also result in an inappropriate decision that lacks scalability, that is, appropriateness to circumstances or "one size fits all" orientation. This approach can lead to "absolutionism" and may create problems with stakeholders.
Other project managers do just the opposite . They complicate an issue or problem and, in turn , do the same for decision making. The result is a "bird's nest" of facts, data, and assumptions that leads only to greater confusion and frustration.
What project managers need to recognize is that decision making often deals with issues and problems on a gray scale. They must define issues or problems clearly and then tailor the decisions by consulting with other stakeholders, even those who do not share the same views. This approach will help prevent oversimplification or overcomplication of an issue or problem and decision making.
This approach requires, therefore, that project managers challenge their own assumptions and those of others. For reasons of security, such challenges are often difficult to face because they may mean admitting being wrong or incomplete.
A decision has two parts : making the decision and its execution. While this sounds like common sense, it is often not exercised. Most project managers make decisions throughout the life cycle of projects, but many of them fail to perform follow-up. Large, complicated projects may pose a problem in this regard. However, on small- or medium- sized projects, this appears to be a smaller problem due to scalability. Nonetheless, project managers must converse with stakeholders to determine whether a decision has been actually executed. Simple declaration is not enough. Stakeholders get occupied with other issues; time passes between the decision and its implementation, and people simply forget about it. Project managers may not have communicated the decision very effectively or people simply did not speak up. Regardless, project managers must constantly follow up on their decisions.
All decisions usually involve trade-offs, that is, sacrificing something to achieve something else. For example, a decision may require sacrificing one goal or objective for another as it relates to cost, schedule, quality, and scope. Of course, in times of unlimited resources this circumstance may not exist. Such moments are few and far between. More often than not, project managers must make trade-offs because resources are scarce ” whether time or money. There is an acronym to describe this scenario: TANSTAAFL, for There Ain't No Such Thing As A Free Lunch. Such trade-off decisions, of course, present substantial challenges to project managers because they will invariably dissatisfy or satisfy certain stakeholders. It is imperative, therefore, that project managers do not, unless circumstances warrant it, make unilateral decisions. They should also effectively communicate their decisions.
Decisions should be made from the perspective of a vision for a project for two major reasons. The first is that it will help prevent scope creep, that is, the tendency to take on additional work that goes beyond what was originally defined. The other reason is that it eases "selling" a decision, as it is relatively self-explanatory. People will tend to find it more acceptable, especially if they did not participate in a decision.
Decision making requires both sides of the brain, left and right. True, analytical, linear thinking (left brain) is important. However, to decide on problems or issues, integrated relational thinking is also important. Overlooking the importance of an integrated perspective can lead to tunnel vision and negative downstream effects on a project.
Use flexibility when adapting different approaches towards decision making. Some project managers may find that elaborate mathematical calculations are preferable to select the best alternative, particularly when time is available. Or, they may take an intuitive approach that emphasizes "gut feel." To be reliable, however, intuition depends largely on experience Another option is to use an experiential approach. Instead, project managers rely on experience, which allows them to recognize patterns and identify key issues or drivers to "visualize" effects.
With these caveats in mind, it becomes easier to understand and deal with the human side of decision making. People add complications to the decision-making process. Leadership is about dealing with the human side.
 Edward De Bono, Practical Thinking , Penguin Books, London, 1971, p. 32.
 Daniel Goleman, Emotional Intelligence , Bantam Books, New York, 1995, pp. 85 “86.
 Thomas Gordon, Leadership Effectiveness Training (L.E.T.) , Bantam Books, Toronto, 1980, p. 38.