Delphi method

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Introduction[edit | edit source]

The Delphi method is a process mostly used in research and economics, that aims to collect opinions on a particular research question or specific topic, to gain consensus. The opinions are collected from a group of experts that are not physically assembled, normally through questionnaires. [1]

This technique was firstly developed in the 1950s for military actions as a systematic method to anticipate events. After it became a popular tool for business forecasting, and in the 2000s gained acceptance in the scientific community. [2] The name of this method refers to the temple of the ancient Greece that hosted the Oracle of Delphi, famous for the ability to make prophecies.  

Overview of the Delphi method[edit | edit source]

The premise of this method is that pooled intelligence can enhance individual judgement. [2]In practice, the researcher choses the panel of experts, and develops a series of iterative questionnaires. Panelists reply anonymously to the iterative questionnaires, where every questionnaire sent represent a round.

At every round, panelists receive feedback in the form of a statistical representation of the overall group’s response. The goal of the multiple iterations is to reduce the range of responses and gain consensus based on criteria chosen a priori by the researcher. [2]

The critical issues of conducting a Delphi study are the development of the questionnaire, the definition of consensus and the interpretation of non-consensus, criteria for selection of the panel and data analysis. [3]


Advantages[edit | edit source]

Delphi studies allow the panel of participants to reconsider and reflect on their opinions in light of the contribution of other peers’ views. This factor of reflection and opinion sharing is missing in all the other study designs and is an important value for healthcare practice. [3] Another important factor is the anonymity among the experts, so that opinions and opinion changes are not influenced by any factor rather than the feedback from the iterative surveys.

Disadvantages[edit | edit source]

Delphi studies can be subjected to high drop-out rates of the participants because of the need to complete multiple rounds of surveys. This factor can impact the validity of the study. The flexibility to change opinion that represents an advantage, has also some inconveniences. In fact, it can occur the bias for which participants adapt to the opinion of the majority, that is visible through the feedbacks. [3]

Examples of Delphi studies in physiotherapy[edit | edit source]

  • A Delphi study investigated consensus among expert physiotherapists about the management of low back pain. This study analyses a problem about which clinical guidelines exist, but there is no consensus on the actual physiotherapy management. This study conducted in a three-round set of questions. The panel was composed of 34 physiotherapists expert about this topic. The responses were ranked on a five-point Likert scale. In three rounds the predetermined point. [5]
  • A Delphi design was used to define what is the Bobath concept through the view of fifteen physiotherapists expert in the field. The study is composed of four rounds. The five-point Likert scale was used to determine the level of agreement. [6]

Use in healthcare research[edit | edit source]

The Delphi method is used in healthcare mostly to gain consensus in the development of guidelines or treatment protocols, and when there is limited or conflicting evidence. For example, the Delphi method was used for the development of healthcare design guidance tools such as the Safety Risk Assessment (SRA) for Healthcare Settings. [7] The Delphi technique is becoming a popular research strategy in healthcare because it allows to analyze both qualitative and quantitative data. [1]

References[edit | edit source]

  1. 1.0 1.1 de Villiers MR, de Villiers PJ, Kent AP. The Delphi technique in health sciences education research. Med Teach. 2005 Nov; 27(7):639-43. doi: 10.1080/13611260500069947. PMID: 16332558.
  2. 2.0 2.1 2.2 Taylor E. We Agree, Don’t We? The Delphi Method for Health Environments Research. HERD: Health Environments Research & Design Journal. 2020;13(1):11-23. doi:10.1177/1937586719887709
  3. 3.0 3.1 3.2 Barrett D, Heale R What are Delphi studies? Evidence-Based Nursing 2020; 23:68-69.
  4. GreggU. Delphi Technique. Available from: [last accessed: 20/05/2022]
  5. Ferguson FC, Brownlee M, Webster V. A Delphi study investigating consensus among expert physiotherapists in relation to the management of low back pain. Musculoskeletal Care. 2008 Dec;6(4):197-210. doi: 10.1002/msc.126. PMID: 18311847
  6. Raine S. Defining the Bobath concept using the Delphi technique. Physiotherapy Research International. March 2009. Vol. 11(1), pp 4-13.
  7. The Center for Health Design, 2017; Taylor, Joseph, Quan, & Nanda, 2014.