Group decision making
Group decision making (also known as collaborative decision making) is a situation faced when individuals collectively make a choice from the alternatives before them. This decision is no longer attributable to any single individual who is a member of the group. This is because all the individuals and social group processes such as social influence contribute to the outcome. The decisions made by groups are often different from those made by individuals. Group polarization is one clear example: groups tend to make decisions that are more extreme than those of its individual members, in the direction of the individual inclinations.
There is much debate as to whether this difference results in decisions that are better or worse. According to the idea of synergy, decisions made collectively tend to be more effective than decisions made by a single individual. However, there are also examples where the decisions made by a group are flawed, such as the Bay of Pigs Invasion, the incident on which the Groupthink model of group decision making is based.
Factors that impact other social group behaviours also affect group decisions. For example, groups high in cohesion, in combination with other antecedent conditions (e.g. ideological homogeneity and insulation from dissenting opinions) have been noted to have a negative effect on group decision making and hence on group effectiveness. Moreover, when individuals make decisions as part of a group, there is a tendency to exhibit a bias towards discussing shared information (i.e., shared information bias), as opposed to unshared information.
Group Decision Making in Psychology 
The social identity approach suggests a more general approach to group decision making than the popular Groupthink model which is a narrow look at situations where group decision making is flawed. Social identity analysis suggests that the changes which occur during collective decision making is part of rational psychological processes which build on the essence of the group in ways that are psychologically efficient, grounded in the social reality experienced by members of the group and have the potential to have a positive impact on society.
Formal Systems 
- Consensus decision-making tries to avoid "winners" and "losers". Consensus requires that a majority approve a given course of action, but that the minority agree to go along with the course of action. In other words, if the minority opposes the course of action, consensus requires that the course of action be modified to remove objectionable features.
- Voting-based methods
- Range voting lets each member score one or more of the available options. The option with the highest average is chosen. This method has experimentally been shown to produce the lowest Bayesian regret among common voting methods, even when voters are strategic.
- Majority requires support from more than 50% of the members of the group. Thus, the bar for action is lower than with unanimity and a group of "losers" is implicit to this rule.
- Plurality, where the largest block in a group decides, even if it falls short of a majority.
- Delphi method is structured communication technique for groups, originally developed for collaborative forecasting but has also been used for policy making
- Dotmocracy is a facilitation method that relies on the use of special forms called Dotmocracy Sheets to allow large groups to collectively brainstorm and recognize agreement on an unlimited number of ideas they have authored.
Decision making in groups is sometimes examined separately as process and outcome. Process refers to the group interactions. Some relevant ideas include coalitions among participants as well as influence and persuasion. The use of politics is often judged negatively, but it is a useful way to approach problems when preferences among actors are in conflict, when dependencies exist that cannot be avoided, when there are no super-ordinate authorities, and when the technical or scientific merit of the options is ambiguous.
In addition to the different processes involved in making decisions, group decision support systems (GDSS) may have different decision rules. A decision rule is the GDSS protocol a group uses to choose among scenario planning alternatives.
- Gathering involves all participants acknowledging each other's needs and opinions and tends towards a problem solving approach in which as many needs and opinions as possible can be satisfied. It allows for multiple outcomes and does not require agreement from some for others to act.
- Sub-committee involves assigning responsibility for evaluation of a decision to a sub-set of a larger group, which then comes back to the larger group with recommendations for action. Using a sub-committee is more common in larger governance groups, such as a legislature. Sometimes a sub-committee includes those individuals most affected by a decision, although at other times it is useful for the larger group to have a sub-committee that involves more neutral participants.
- Participatory, where each actor would have a say in decisions directly proportionate to the degree that particular decision affects him or her. Those not affected by a decision would have no say and those exclusively affected by a decision would have full say. Likewise, those most affected would have the most say while those least affected would have the least say.
Plurality and dictatorship are less desirable as decision rules because they do not require the involvement of the broader group to determine a choice. Thus, they do not engender commitment to the course of action chosen. An absence of commitment from individuals in the group can be problematic during the implementation phase of a decision.
There are no perfect decision making rules. Depending on how the rules are implemented in practice and the situation, all of these can lead to situations where either no decision is made, or to situations where decisions made are inconsistent with one another over time.
Social decision schemes 
Sometimes, groups may have established and clearly defined standards for making decisions, such as bylaws and statutes. However, it is often the case that the decision making process is less formal, and might even be implicitly accepted. Social decision schemes are the methods used by a group to combine individual responses to come up with a single group decision. There are a number of these schemes, but the following are the most common:
- Delegating decisions: where an individual, subgroup, or external party makes the decision for the group. For instance, in an authority scheme, the leader makes the decision; or in an oligarchy, a coalition will make the decision.
- Averaging decisions: this is when each individual member makes an independent private decision, which are later averaged together to give a nominal group decision.
- Plurality decisions: where members of the group vote on their preferences, either privately or publicly. The decision will then be based on these votes in a majority-rules scheme, in a more substantial two-thirds majority scheme, or in a Borda count method that uses ranking methods.
- Unanimous decisions: this is a consensus scheme, whereby the group discusses the issue until it reaches a unanimous agreement. This decision rule is what dictates the decision making for most juries.
- Random decision: in this type of scheme, the group will leave the choice up to chance. For example, picking a number between 1 and 10, or flipping a coin.
There are strengths and weaknesses to each of these social decision schemes. Delegation saves time and is a good method for less important decisions, but ignored members might react negatively. Averaging responses will cancel out extreme opinions, but the final decision might disappoint many members. Plurality is the most consistent scheme when superior decisions are being made, and it involves the least amount of effort. Voting, however, may lead to members feeling alienated when they lose a close vote, or to internal politics, or to conformity to other opinions. Consensus schemes involve members more deeply, and tend to lead to high levels of commitment. But, it might be difficult for the group to reach such decisions.
Normative Model of Decision Making 
Groups have many advantages and disadvantages when making decisions. Groups, by definition, are composed of two or more people, and for this reason naturally have access to more information and have a greater capacity to process this information. However, they also present a number of liabilities to decision making, such as requiring more time to make choices and by consequence rushing to a low quality agreement in order to be timely. Some issues are also so simple that a group decision-making process leads to too many cooks in the kitchen: for such trivial issues, having a group make the decision is overkill and can lead to failure. Because groups offer both advantages and disadvantages in making decisions, Victor Vroom developed a normative model of decision making  that suggests different decision making methods should be selected depending on the situation. In this model, Vroom identified five different decision making processes.
Decide- Here, the leader of the group uses other group members as sources of information, but makes the final decision independently, and does not explain to group members why she/he requires that information.
Consult (individual)- The leader talks to each group member alone, never consulting with the entire group as a whole. She/he then makes the final decision in light of this individually-obtained information.
Consult (group)- The leader consults the entire group at once, asking for opinions and information, and then comes to a decision.
Facilitate- In this strategy, the leader takes on a cooperative holistic approach, collaborating with the group as a whole as they work toward a unified and consensual decision. The leader is non-directive, and never imposes a particular solution on the group. In this case, the final decision is the one made by the group, and not the leader.
Delegate- The leader takes a backseat approach, passing the problem over to the group. The leader is supportive, but allows the group to come to a decision without their direct collaboration.
Decision Support Systems 
The idea of using computerized support systems is discussed by James Reason under the heading of intelligent decision support systems in his work on the topic of human error. James Reason notes that events subsequent to The Three Mile accident have not inspired great confidence in the efficacy of some of these methods. In the Davis-Besse accident, for example, both independent safety parameter display systems were out of action before and during the event.
Decision making software is essential for autonomous robots and for different forms of active decision support for industrial operators, designers and managers.
Due to the large number of considerations involved in many decisions, computer-based decision support systems (DSS) have been developed to assist decision makers in considering the implications of various courses of thinking. They can help reduce the risk of human errors. DSSs which try to realize some human/cognitive decision making functions are called Intelligent Decision Support Systems (IDSS), see for ex. "An Approach to the Intelligent Decision Advisor (IDA) for Emergency Managers, 1999". On the other hand, an active/intelligent DSS is an important tool for the design of complex engineering systems and the management of large technological and business projects, see also: "Decision engineering, an approach to Business Process Reengineering (BPR) in a strained industrial and business environment".
Group Discussion Pitfalls 
Groups have greater informational and motivational resources, and therefore have the potential to outperform individuals. However they do not always reach this potential. Groups often lack proper communication skills. On the sender side this means that group members may lack the skills needed to express themselves clearly. On the receiver side this means that miscommunication can result from information processing limitations and faulty listening habits of human beings.
It is also the case that groups sometimes use discussion to avoid rather than make a decision. Avoidance tactics include the following:
• Procrastination. Replacing high priority tasks with tasks of lower priority. The group postpones the decision rather than studying the alternatives and discussing their relative merits.
• Bolstering. The group may quickly or arbitrarily formulate a decision without thinking things through to completion. They then bolster their decision by exaggerating the favorable consequences of the decision and minimizing the importance of unfavorable consequences.
• Denying responsibility. The group delegates the decision to a subcommittee or diffuses accountability throughout the entire group, thereby avoiding responsibility.
• Muddling through. The group muddles through the issue by considering only a very narrow range of alternatives that differ to only a small degree from the existing choice.
• Satisficing. A combination of satisfy and suffice. Members accept a low risk, easy solution instead of searching for the best solution.
• Trivializing the discussion. The group will avoid dealing with larger issues by focusing on minor issues.
Two fundamental laws that groups all too often obey:
Parksinson’s Law: A task will expand to fill the time available for its completion. (Ex: Groups that plan to meet for an hour stay for the duration).
Law of triviality: The amount of time a group spends discussing an issue will be in inverse proportion to the consequentiality of the issue (Ex: Committee discusses $20 million stadium fund for 3 minutes).
Cognitive Limitations and Subsequent Errors Individuals in a group decision-making setting are often functioning under substantial cognitive demands. As a result, cognitive and motivational biases can often impact group decision making. According to, there are three categories of potential biases that a group can fall victim to when engaging in decision-making.
1. Sins of Commission: The misuse, or inappropriate use of information. These can include: a) Belief perseverance: when a group utilises information in their decision making, which has already been deemed inaccurate b)Sunk cost bias: when a group remains committed to a given plan of action solely because an investment has already been made in that given plan, despite its usefulness c)Extra-evidentiary bias: A group choosing to rely on information, despite being explicitly told it should be ignored d)Hindsight bias: When group members falsely over-estimate how accurate their past knowledge of a given outcome
2. Sins of Omission: The overlooking of useful information. These can include: a)Base rate bias: When group members ignore applicable information they have concerning basic trends/tendencies b)Fundamental attribution error: When group members base their decisions on inaccurate appraisals of individuals behaviour
3. Sins of Imprecision: Relying too heavily on heuristics, which over-simplify complex decisions. These can include: a) Availability heuristic: when group members rely on information that is readily available, in making a decision. b)Conjunctive bias: When groups are not aware that the probability of one event occurring will always be greater than the probability of two events occurring together. c) Representativeness heuristic: when group members rely too heavily on decision-making factors that seem meaningful, but in reality are somewhat misleading.
Indeed, in a group-decision making context, it would be beneficial for group members to be cognisant of the aforementioned biases and errors which may affect their ability to make informed and tactful decisions.
See also 
- Moscovici, S.; M. Zavalloni (1969). "The group as a polarizer of attitudes". Journal of Personality and Social Psychology 12 (2): 125–135. DOI:10.1037/h0027568
- Janis, I. L. (1972). Victims of groupthink. Boston, MA: Houghton-Mifflin.
- Haslam, S. A. (2001). Psychology in organisations: The social identity approach. London: Sage. p. 177.
- Hastie; Kameda (2005). Missing or empty
- Davis et al. (1988). Missing or empty
- Kameda et al. (2002). Missing or empty
- Forsyth, D. R. (2006). Decision Making. In Forsyth, D. R. , Group Dynamics (5th Ed.) (P. 317-349) Belmont: CA, Wadsworth, Cengage Learning.
- Vroom, V. H. (2003). Educating managers in decision making and leadership. Management Decision, 10, 968–978
- James Reason (1990). Human Error. Ashgate. ISBN 1-84014-104-2