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Economics, Education, and Policy: Review Article

Review of Experimental Studies in Social Psychology of Small Groups When an Optimal Choice Exists and Application to Operating Room Management Decision-Making

Prahl, Andrew*; Dexter, Franklin MD, PhD; Braun, Michael T. MA*; Van Swol, Lyn PhD

Author Information
doi: 10.1213/ANE.0b013e3182a0eed1
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A previous review considered why, if a neurological surgeon uses ≥11 hours of operating room (OR) time on more than two-third of Mondays, many managers (leaders) would still plan only 10 hours of staffing on Mondays for their OR.1 Similarly, suppose that usually all other ORs finish earlier on Mondays and the anesthesia department uses teams on workdays (e.g., neurological versus regional anesthesia). Many anesthesia groups’ managers would not use these data when planning the staff schedule including who works late each day if necessary.2 Although some may attribute managers’ suboptimal decisions to “politics,” inertia, or other such factors, the evidence supports psychological bias.2–12

Hospitals’ operational priorities can be influenced both by lack of scientific knowledge and psychological biases. For example, the fact that fewer than half of surgical cases take longer than scheduled was not known by most OR staff (32%, P = 0.008).7 Also, none of the 32% of survey participants who knew that most cases are completed within their scheduled times applied that knowledge to answer a question on late starts correctly (P = 0.0002).7 The reason was that participants shared a psychological bias that surgical cases do not start early but either on time or late, as do clinic appointments and bus and train departures.7,11

On the day of surgery, anesthesiologists and other decision-makers often make managerial decisions using common rules-of-thumb (i.e., “heuristics”). For example, consistent and rational management decisions on the day of surgery cannot be made other than based on reducing hours of overutilized time.5,6,12–14,a Yet, even when educated that particular decision choices are optimal, clinicians persist in trying to keep each provider working continuously.6,12 Such behavior, although optimal for an individual OR, is suboptimal when there are multiple ORs that need to be considered.6 This bias occurs throughout the surgical suite, not just at the OR control desk.10

In the setting of these biases,1,4–7,10–12 management decisions are not improved significantly by frequent feedback or education.1 Rather, decision-support systems help by providing recommendations.1 Education increases leaders’ trust in the recommendations and their skill at evaluating when a recommendation may be based on incomplete information.5,15,16 Suppose, however, that the leader must work with other stakeholders (e.g., president of the anesthesia group, hospital executive, and/or surgeons), who lack interest in learning the science, but nonetheless expect to participate in decision-making. It is unknown what the leader should do for his/her organization to make optimal decisions.

In the current article, we seek to learn why small groups of anesthesiologists, surgeons, nurses, and administrators routinely make poor operational decisions even when the scientific answer is known by the leader. We do this by reviewing experimental studies from communication and psychology that provide insight into understanding decision-making with input from others in the context of OR management (Table 1). We test the hypothesis that the OR management decisions are suboptimal when the knowledge cannot be demonstrated to other group members and the knowledge clashes with the opinions of the majority of group members, even when the majority opinion is incorrect. The sequence of the review is:

Table 1
Table 1:
Descriptions of Experimental Social Psychology Studies
  • Section 2. Shared and unshared information;
  • Section 3. Decision quality with and without unshared information;
  • Section 4. Group susceptibility to cognitive biases;
  • Section 5. Conditions under which a correct minority can influence a group;
  • Section 6. Consideration of appropriate leadership style and perceptions of such leadership; and
  • Section 7. Discussion.

Each of the terms is described in the corresponding section(s).


Shared information is information that group members all know before group discussion. Unshared information is information that is known only to 1 group member before discussion and becomes known to others when mentioned during the discussion. For OR management, shared information would refer to the rules-of-thumb (heuristics) that make intuitive sense and often seem “close enough” (e.g., staffing is planned based on the average workload). Conversely, unshared information would refer to mathematics involving optimal choices (e.g., “stochastic optimization”b). The authors are unaware of anyone who claims intuition for the mathematically optimal solutions, even in retrospect. Education does not provide intuition, just trust in the mathematics.15,16

Refs. 17 to 28 describe individual studies with quantitative data about shared and unshared information discussed in small groups. The studies are summarized in Table 1. Figure 1 shows the standardized differences of items of shared compared to unshared information mentioned during small group discussion.29 The data from each study were used to calculate an effect size.29 For example, groups discussed an average of 10.72 items of shared information vs 7.05 items of unshared information.17 The pooled standard deviation for both groups was 0.955. The calculated effect size was the standardized mean difference of 3.84, where 3.84 = (10.72–7.05)/0.955. The standardized mean difference listed in Figure 1 for Ref. 17 is 3.84. Examination of Figure 1 shows that the minimum effect size equaled 1.25.17–28Figure 1 shows that studies consistently show that shared information is more influential during group discussions than is unshared information.29

Figure 1
Figure 1:
Groups discuss shared information more than unshared information. Other results on the same topic are summarized in Table 2. The red numbers are the Reference numbers of each study as listed in Table 1. The horizontal axis is the effect size, specifically the standardized mean difference.29 The standardized mean differences are from Table 1 of Reference Ref. 29, but there are fewer papers in our Figure 1 than in Table 1 of Reference Ref. 29 because we considered studies relevant to our application to OR management. An example of the calculation of the standardized mean differences is described in Section 2 “Shared and Unshared Information” using Ref. 17.

Shared information is discussed more and focused on, even when high quality decision-making depends on the unshared information (see Section 3, below).29 For example, Ref. 18 considers medical teams assigned a hypothetical patient case for diagnosis.18 Before meeting in groups of 3, participants watched a video that provided them with information in the following manner:

“Two sets of three patient videotapes were created for each case. The three videotapes within each set were seen by different team members and differed from one another with respect to the specific items of information they contained. Each videotape contained some information that was also present in the other two tapes in the same set (shared information) and some that was present in that tape alone (unshared information). Roughly, two thirds of the information for each case was shared and thus included in all three videotapes. The rest was unshared and was divided about equally among the three videotapes. Taken as a whole, however, the three videotapes within each set contained all of the available case information [needed to produce a correct diagnosis].”18

The subsequent group discussion was recorded and coded by researchers so the amount of shared and unshared information discussed could be measured.18 The effect size of 3.70 is shown with a circle around Ref. 18 in Figure 1.29 As described in the preceding paragraph, the 3.70 is the standardized mean difference between amounts of shared versus unshared information.29

There are 3 main reasons why shared information is more influential than unshared information. First more group members have access to shared information and so shared information is mentioned more in discussions (Table 2).30,31

Table 2
Table 2:
Findings Related to Section 2 “Shared and Unshared Information” and Section 3 “Decision Quality With and Without Unshared Information”

Second, shared information influences all group members’ prediscussion opinions. Members mention shared information more often when justifying their individual opinions.32 When unshared information is mentioned, other group members tend to discount it because it did not help to form their initial opinion and initial opinions bias reaction to new information.32 Thus, when a group member mentions both shared and unshared information, shared information is more likely to be repeated and more likely to influence the group decision.18

The final reason why shared information is more influential than unshared information is that shared information validates what group members already know (Table 2).30 When a group member mentions shared information, other members recognize that information and can validate it against their own knowledge. This increases the perceived expertise of a group member who mentions shared information because shared information has more perceived validity in the eyes of other group members.30 Further, other members may feel validated that someone mentions information that they know.30 Having a group member’s knowledge validated makes the member feel more competent.30 Members often respond positively to shared information being mentioned and may nod or affirm the information and each other when that information is being shared.33

Researchers have consistently found that if a group member has more unshared information than others do in the group, the member will speak less and contribute less information.31 A group member mentioning unshared information, especially unshared information that is not supportive of the group’s initial majority opinion, has 2 obstacles toward getting that information integrated into the group discussion (Table 2). First, if the unshared information is inconsistent with the majority of other group members’ preferences, it is likely to be discounted by the rest of the group.32 Second, the information does not validate other members’ current stores of information and knowledge and is not positively reinforcing.30 Thus, unshared information often receives a negative reaction from other group members and is unlikely to be repeated by either the member introducing the information or other group members.31 The negative reaction to the unshared information may reduce the group member’s motivation to try to reintroduce it to the discussion.31


Shared information can help groups create a common ground and increases members’ perceptions of each other’s knowledge and competence (Table 2).27,30,33 Suppose a group member holds key unshared information that points to a superior alternative unsupported by the majority of group members. Research has consistently found that small groups not only ignore this key unshared information (Fig. 1) but also fail to adopt the superior alternative (Fig. 2).22,25,26,29,34–37

Figure 2
Figure 2:
Groups without hidden profile condition produce correct decision or diagnosis more often than groups in hidden profile condition. Other results on the same topic are summarized in Table 2. The red numbers are the Reference numbers of each study as listed in Table 1. Whereas the effect sizes of Figure 1 are standardized mean differences, the effect sizes of this figure are odds ratios. The dotted vertical line is at an odds ratio of 1.0. Most22 , 25 , 32 , 34–37 of the odds ratios are from Table 2 of Ref. 29, but there are fewer papers in our Figure 2 than in Table 2 of Ref. 29 because we limited considered studies relevant to our application to OR management. An example of the calculation of the odds ratio is described in Section 3, “Decision Quality With and Without Unshared Information,” using Ref. 26. In addition to the odds ratios (effect sizes) shown, 2 additional studies reported the same finding but reported “P < 0.01” without effect sizes.17 , 18

In “hidden profile” studies, shared information given to group members support an inferior alternative. The superior alternative is supported by unshared information given to only 1 member of the group before discussion. The only way for the group to uncover the superior alternative is through discussion and integration of the unshared information. The performance of the group with the hidden profile is compared against the performance of control groups in which each member has all of the information (i.e., nothing is hidden from anyone).

Several studies compared groups operating in a hidden profile condition to groups in which all information is shared among all group members before the discussion.29 The effect sizes are odds ratios, specifically the odds of the control groups producing a correct decision versus the odds of the hidden profile groups producing a correct decision.29 An odds ratio of 1.00 implies that both groups had the same odds of producing a correct decision. An odds ratio of 107 implies that the control group’s odds of producing a correct decision were 107 times the odds of the hidden profile group. For example, for Ref. 26, the percentage of correct group decisions was 89% for the control groups and 7% for the hidden profile groups. The odds ratio equaled 107, where 107 = (89%/[100% − 89%])/(7%/[100% − 7%]).26Figure 2 shows that control groups consistently produce superior decision quality versus hidden profile groups.29

Importantly, these study results apply when an optimal choice exists (e.g., for many OR management operational decisions), not in general to small groups (see Discussion).


Several biases in OR management are caused by humans’ limited abilities to estimate tails of probability distributions in their heads (i.e., humans are not mathematical computers).1,11 For example, managers have a pull-to-center bias that results in making decisions towards the mean when a larger percentile is more appropriate (e.g., for staffing).1,38,39 They express concerns about staff working late and patients waiting for surgery, but then make decisions that cause these consequences to occur.1,6,12,39 Managers also rely on recent data even when a longer time series of data would be better (“recency bias”).1

The relevant question is whether groups are less susceptible to biases that involve probabilistic decision-making. Studies investigating analogous biases are summarized in Table 3.40–43 In general, small groups exaggerate these biases (i.e., groups make worse decisions than individuals do) when most or all group members share the bias, a condition true in OR management problems.1,5–8,10–12

Table 3
Table 3:
Findings Related to Section 4 “Group Susceptibility to Cognitive Biases”


For group decisions with a correct or optimal choice, research has investigated how many group members must support the correct/optimal choice before the group is willing to accept the answer.44 The key variable is demonstrability. The easier the correct/optimal choice is to demonstrate to other group members, the fewer correct group members are needed for the group to adopt the correct/optimal choice.44 For example, moderately easy math problems are often easy to demonstrate; small groups in which only 1 member knows the answer usually adopt the correct solution (P < 0.0001).44

For a task to be considered highly demonstrable, the group must first operate using the same language and agree that a given problem indeed has a correct answer.44 If the group members are using different languages or have different perceptions of the task, then the solution is not demonstrable.44 OR management fails to meet this criterion because inconsistent vocabulary is the norm, and perceptions of problems are heterogeneous due to inconsistency in scientific knowledge.5,7,15,45–47

Second, all group members must be able to recognize the correct solution when it is presented.44 If a group member cannot discern correct from incorrect answers, then the solution is not demonstrable. In OR management, even experts cannot discern correct from incorrect answers, which is why applying mathematics is useful.1,4–7,10–12

Third, the member(s) who reach the correct answer must have “sufficient ability, motivation, and time to demonstrate the correct answer.”44 If, under time pressure or other constraints, the correct member cannot show other group members why her answer is correct and other answers wrong, then the solution is not demonstrable. For OR management decisions made on the day of surgery, even if a small group forms ad hoc to make a decision, there is insufficient time for an expert to demonstrate why a decision is optimal.5,6,9–12 The most that is feasible is to memorize some typical scenarios and adapt them quickly (e.g., over a couple of minutes) to the situation to show that the decisions are rational.48


Appropriate models of decision-making within an organization differ in the stakeholder participation and depend on the situation (Table 4).49–56 There are 5 approaches to decision-making based on the role of the group leader (i.e., manager):

Table 4
Table 4:
Findings Related to Section 6 “Normative Model of Leader Behavior”
  • Group level decision-making. The leader discusses the issue with the group, does not force his ideas on the group, and accepts the group consensus. The leader’s role is that of chairperson, coordinating the discussion.
  • Consultative type level 2 decision-making. The leader shares the problem with stakeholders as a group and seeks discussion and ideas, but ultimately the decision-maker makes the decision alone.
  • Consultative type level 1 decision-making. The leader shares the problem with stakeholders individually soliciting their input, but then the decision-maker makes the decision alone.
  • Autocratic type level 2 decision-making. The leader solicits information from stakeholders, but not necessarily the decision problem, and then makes the decision alone. The leader may or may not tell the others what the problem is in getting the information from them. The role played by the stakeholders in making the decision is one of providing the necessary information to the leader, rather than generating or evaluating alternative solutions. For example, to obtain updates on the time remaining in late running cases, implementation of instant messages sent to anesthesia workstations was done without education, announcement, or buy-in.57 There were, however, 1:1 meetings between the leader doing the implementation and his colleagues for the leader to acquire information (e.g., perceived usability of the display of the remaining times).
  • Autocratic type level 1 decision-making. The leader makes the decision alone without any input.

In the setting of the biases summarized in Section 1, and the findings of Sections 2–5, there would appear to be only 2 possible choices for the leader making operational decisions in surgical suites. If there are many stakeholders who have received substantial education in the relevant OR management science, then a consultative type of decision-making can be used. Otherwise, autocratic type level 2 style would be the appropriate choice.

Despite the finding, managers generally do not apply the autocratic style, even when it is appropriate (Table 4).51 Leaders who appropriately apply the autocratic style are perceived by their (simulated) boss to be more competent, to have favorable behavior, and to be more dynamic.52 They are also rated by (simulated) subordinates as less likeable.52 This finding seems important for OR nursing directors, since they tend to be evaluated less based on decision quality than on the perceptions of their subordinate nurses.58 Research on procedural justice has found that people rate their leader’s decisions as higher quality and are more willing to accept the decision when they can meet as a group to express their opinion.53 They rate the decision as fairer when they can change the decision and/or express an opinion.54–56


Many OR management decisions have optimal choices. However, the decisions are not intuitive even in retrospect, partly because of multiple psychological biases (Section 1). Education sufficient for most basic decisions takes 35 hours for people who use statistics often in their work and 50 hours if is also includes statistics review.15,16 Unless the majority of group members have such education, there is little chance that the science will be a focus of discussion (Section 2).29 When the leader alone has the OR management scientific knowledge, a quality decision is less likely than when the small group has the requisite education (Section 3).29 Groups exaggerate psychological biases similar to those in OR management (Section 4). A leader cannot demonstrate the appropriateness of the solution (Section 5). Leaders will find the most success if they do not bring OR management operational decisions to groups, but instead act autocratically while obtaining necessary information in 1:1 conversations (Section 6). The only route we identified for an effective OR leader to be considered likeable and for optimal choices to be considered fair is through education of his/her colleagues and subordinates.15,16 Trying to persuade a group that an optimal decision is wise (e.g., by providing a research study or having a consultant make a presentation) will usually be unsuccessful (Sections 2 and 3).

Limitations to the usefulness of our review include our having only partial knowledge of the tools that should be provided to the OR leader. First, we know that anesthesia-hospital agreements (“contracts”) help sustain the leader’s decisions.59 The contract protects both parties from an individual or group, without training, who nonetheless suggests changes based on a “common sense” approach (see 3rd paragraph of Introduction). Second, we know that adapted scenarios (i.e., with appropriate cues such as specific ORs and surgeon names) can help the autocratic leader to obtain the knowledge necessary to make good decisions.48 However, third, we do not know how best to provide feedback to the leader. Accurate feedback is unlikely to come from colleagues and subordinates who lack the requisite knowledge of OR management science. Should OR leaders discuss and critique planned decisions using computer decision-support system, e-mail or Web conferencing with an expert, and/or discussion forums with other educated leaders? Future research should assess the impact of feedback on the quality of the leader’s decision (e.g., increasing confidence that his/her knowledge is correct in the face of dissent).

Our review was limited to problems relevant to OR management with optimal choices (Section 1), and should not be applied to other domains. For example, consider a journal Editor held responsible for the integrity of the journal, but also needing to be liked and have decisions considered fair by the editorial board. Bibliometric assessment shows that most surveys in anesthesia journals lack appropriate statements of hypotheses and corresponding confidence intervals.60 We think that a brief (e.g., 20 minutes) presentation would be sufficient to educate and persuade the editorial board about the value of following standards for the reporting of surveys. This is because the decisions are intuitive in retrospect (Section 1), one article60 provides sufficient education (Section 2), multiple individuals on the editorial board will have heard of the issues previously (Section 3), psychological biases are not dominant (Section 4), and the decision’s appropriateness can be demonstrated (Section 5).

Our review was limited to problems relevant to OR management with optimal choices (Section 1), and also should not be applied to other types of OR management problems. For example, suppose that there are daily periods of waiting in ORs because there is only 1 cytopathologist and not sufficient total work for a second cytopathologist to be hired. Group level decision-making is appropriate for this scenario, because there is no one optimal decision, commitment of the stakeholders to the decision is important, and the leader likely cannot even impose a decision if he/she wanted to do so (Section 6). OR management leadership may be divided with an autocratic-style leader (e.g., an anesthesiologist) handling the decisions with optimal choices and a different participative style leader chairing committees (e.g., a surgeon). Alternatively, since decisions with optimal choices necessitate an autocratic style, perhaps it is better that the same (autocratic) leader also chairs committees addressing scenarios without optimal choices. Future organizational behavior studies can assess whether encouraging and using feedback and group participation on some decisions increases trust and perceptions of fairness that transfer to autocratic decisions.


Franklin Dexter is the Statistical Editor and Section Editor for Economics, Education, and Policy for the Journal. This manuscript was handled by Dr. Steven Shafer, Editor-in-Chief, and Dr. Dexter was not involved in any way with the editorial process or decision.


Name: Andrew Prahl.

Contribution: This author helped design the study, perform the study, and prepare the manuscript.

Attestation: This author approved the final manuscript.

Conflicts of Interest: The author has no conflicts of interest to declare.

Name: Franklin Dexter, MD PhD.

Contribution: This author helped design the study, perform the study, and prepare the manuscript.

Attestation: This author approved the final manuscript.

Conflicts of Interest: The University of Iowa, Department of Anesthesia, Division of Management Consulting offers a course designed to meet the criteria considered in the Discussion, Operations Research for Surgical Services. Income is used to fund research. FD has tenure and receives no funds personally, including honoraria, other than his salary and allowable expense reimbursements from the University of Iowa. He and his family have no financial holdings in any company related to his work, other than indirectly through mutual funds for retirement.

Name: Michael T. Braun, MA.

Contribution: This author helped perform the study.

Attestation: This author approved the final manuscript.

Conflicts of Interest: The author has no conflicts of interest to declare.

Name: Lyn Van Swol, PhD.

Contribution: This author helped design the study, perform the study, and prepare the manuscript.

Attestation: This author approved the final manuscript.

Conflicts of Interest: The author has no conflicts of interest to declare.


a Reducing overutilized OR time is the same as reducing overtime provided staff schedules (shifts) match allocated hours of OR time; thus, we use the more general term “overutilized OR time.” Reducing the hours of overutilized OR time is a lower priority than performing scheduled cases, because otherwise absence of overutilized time would be assured by performing no surgery.5,13 Reducing tardiness from scheduled start times is a lower priority than reducing the hours of overutilized OR time, because otherwise long gaps would be scheduled between successive cases.5,13,14 Increasing personal satisfaction (e.g., of surgeons) is a lower priority than reducing the hours of overutilized OR time, because otherwise all ORs would be available 24 hours a day, 7 days per week.5,13
Cited Here

b Readers can refer to Accessed March 10, 2013.
Cited Here


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