The quick and accurate estimation of design effort can be make or break for all but the largest of product design consultancies. Traditional design project planning see designers being taken away from the metaphorical drawing board to spend time assessing project briefs and estimating workloads. Typically these designers base these estimates on their tacit knowledge and experience, and for the most part, they are accurate. However, this is time-consuming and therefore (indirectly) costly, as time spent planning, is not time spent designing. Many more sophisticated approaches for estimating design effort have been developed, but many require large bodies of past data and sophisticated analysis, such as artificial neural networks; and others have highly-specific use cases.

This paper proposes a new method to develop a design effort estimation tool for product design consultancies. This method captures the tacit knowledge and experience of design team members and the tool replicates it quickly and effectively; graphically modelling factors that influence design effort needs in product design projects.

Design effort, the amount of time required to complete a project or task (Salam et al., 2009; Salam and Bhuiyan, 2016), is a required resource for any design project which can be influenced by a number of factors. Estimating design effort is a significant challenge that can be mitigated through an understanding of these influential factors. This understanding is held as tacit knowledge by experts, earned through experience; yet, although these factors vary in type and impact, understanding their details can provide insight and improve future estimations. Some previous methods to estimate design effort identify these factors, either from: expert opinion, or historical data analysis with each approach has advantages and disadvantages.

This paper is comprised of three parts:

A review of published methods and tools for estimating product design effort and whether they consider and identify influential factors; an analysis of possible trends in the identification of factors influencing product design project length; and a new method for identifying the influential factors of product design project length.