Among the most important of all the decisions the world's people will ever make are their decisions about how to make decisions.
Choosing by Advantages (CBA) is a collaborative and transparent decision-making system developed by Jim Suhr, which comprises of multiple methods. CBA includes methods for virtually all types of decisions, from very simple to very complex (Suhr 1999). Perhaps the most used CBA method is the Tabular Method, which is used to choose among two or more mutually exclusive alternatives that are not of equal cost. Examples of decisions where a team needs to choose from mutually exclusive alternatives are in everyday business include: choosing a building material, a general contractor, an equipment, a building design, and who to hire. The CBA Tabular Method can be used for moderately complex to very complex decisions, allowing for documenting these decisions in a transparent fashion.
The main purpose of the CBA method is to help decision makers to differentiate alternatives and to understand the importance of those differences. In CBA, decisions are based on advantages of alternatives, which are positive differences, not advantages and disadvantages; this avoids double counting. For example, let’s say John is 6 feet high, and Peter is 5 feet high, the difference in height is one foot. If we use the rule “the taller the better” as criterion for judgment, one foot difference can be seen as an advantage of John or a disadvantage of Peter. Therefore, in CBA we only count the one feet difference as an advantage of John. Then we will find other differences between Peter and John, such as difference in speed or power, and we will set criteria for judgment to describe those differences as advantages. Once the advantages of each alternative are decided, decision makers need to assess the importance of these advantages by making comparisons among them. By following the CBA method, decisions are anchored to relevant facts, and decisions are particular to a given context, such as choosing a Basketball player for the school team.
In order to explain how to use the CBA Tabular Method, I will introduce a very simple example, explaining how Andy, a young engineer, chooses a car to buy following the CBA Tabular Method in 7 steps (Figure 1).
Step 1: Andy identifies alternatives likely to yield important advantages over other alternatives. The alternatives that Andy identified for choosing a car are:
- Toyota Camry Hybrid
- BMW X5 SUV
- Mercedes C Class
Step 2: Andy defines factors with the purpose of differentiating between alternatives. In CBA, it is important to identify which factors will reveal significant differences among alternatives. The factors that he considers are:
- Fuel Economy (mpg)
- Trunk Space (liters)
Step 3: Andy decides on the criteria for judging. Andy will use the criteria to evaluate attributes of alternatives. Andy decided to use the following criteria, relative to each factor:
- Higher is better
- More is better
- More is better
Step 4: Andy summarize the attributes or characteristics of each alternative. Andy have made some research, and then he is able to summarize the attributes of the alternatives in Table 1:
Step 5: Andy identifies the least preferred attribute for each factor, and then decide on the advantage of each alternative’s attribute relative to that least-preferred one.
- The least preferred attribute for factor fuel economy is 18 mpg. Table 2 shows the least preferred attribute underlined. Therefore, the Toyota Camry Hybrid has an advantage of 22 mpg higher than the BMW X5 SUV, and the Mercedes C Class has an advantage of 4 mpg higher than the BMW X5 SUV.
- The least preferred attribute for factor trunk space is 2 liters. Table 2 shows the least preferred attribute underlined. Therefore, both alternatives Toyota Camry Hybrid and Mercedes C Class have an advantage of having 3 more litres compared to the BMW X5 SUV.
- The least preferred attribute for factor Reliability is reliable. Table 2 shows the least preferred attribute underlined. Therefore, the BMW X5 SUV has an advantage of been more reliable than the Toyota Camry Hybrid and Mercedes C Class.
Step 6: Andy decides on the importance of advantages (IofAs). First, Andy selected the paramount advantage, which is the most important advantage among all. In this case, Andy choose the Toyota Camry Hybrid advantage of 22 mpg higher than the BMW X5 SUV as the paramount advantage, because it is the most important difference to him, and he assigned 100 points in the IofAs scale. Second, Andy used the paramount advantage as anchoring point to weigh other advantages by making comparisons. Third, Andy summed the IofAs for each alternative (Table 3).
Andy assigned 20 IofAs to the Mercedes C Class advantage of having 4 mpg higher than the BMW X5 SUV because it is not as important compared to the paramount advantage. Andy assigned 50 IofAs to the Toyota Camry Hybrid and Mercedes C Class advantage of having 3 litres more of trunk space than the BMW X5 SUV because it is a medium difference compared to the paramount advantage. Andy assigned 30 IofAs to the BMW X5 SUV advantage of being more reliable than the Toyota Camry Hybrid and the Mercedes C Class because it is a somehow significant difference compared to the paramount advantage.
Step 7: Finally, Andy evaluates cost data in order to compare IofAs. In this case the Toyota Camry Hybrid has 150 IofAs, which is more than the BMW X5 SUV (30 IofAs) or the Mercedes C Class (70 IofAs). The Toyota Camry Hybrid cost is US$18.000 approximately, the BMW X5 SUV cost is US$ 55000 approximately, and the Mercedes Class C is US$ 40000 approximately. Therefore, the Toyota Camry Hybrid is cheaper in the short term and also in the long term due to fuel economy and also provides the mo. Therefore Andy decides to choose the Toyota Camry Hybrid.
Andy could also reconsider his decision as a whole, incorporating new information, such as other factors, or new alternatives. In that case he could easily update his decision using the CBA tabular method.
Several studies (Arroyo et al., 2012, 2013, 2015) have shown that CBA is helpful in supporting individual and group decision-making, providing a clear rationale for documenting a decision, these has several implications in project management, improving design and construction processes. CBA can help decision makers to avoid late changes and negative iterations due to poor decision-making.
- 1. Arroyo, P., Tommelein, I. D., and Ballard, G. (2012) “Deciding A Sustainable Alternative By ‘Choosing By Advantages’ In The AEC Industry”. IGLC 20th, San Diego, CA.
- 2. Arroyo, P., Tommelein, I., and Ballard, G. (2013). “Using ‘Choosing By Advantages’ to Select Ceiling Tile From a Global Sustainable Perspective.” Proc. 21st Ann. Conf. Int’l. Group for Lean Construction (IGLC), Fortaleza, Brazil, 309-318.
- 3. Arroyo, P., Tommelein, I., and Ballard, G. (2015). “Selecting Globally Sustainable Materials: A Case Study Using Choosing By Advantages” ASCE, J. Constr. Engrg. and Mgmt., in press.
- 4. Suhr, J. (1999). “The choosing by advantages decisionmaking system.” Quorum, Westport, CT, US, 304 pp.
ABOUT THE AUTHOR
Dr. Paz Arroyo completed her PhD at the University of California, Berkeley studying group decision-making methods. She has published numerous peer-review articles in some of the top research conferences and journals. She has a forth coming book on how to make decisions that support sustainable building design and is currently an assistant professor at the Pontificia Universidad Católica de Chile.