Prototype Experiments: Strategies and Trade-offs

One of the main purposes of prototyping is to validate requirements by testing a solution option with internal and/or external stakeholders for perspectives such as problem-solution fit, product-market fit, technical feasibility, and usability.

“One of the main purposes of prototyping is to validate requirements by testing a solution option with internal and/or external stakeholders (Ciriello et al. 2017;Tronvoll et al. 2017) for perspectives, such as problem-solution fit, product-market fit, technical feasibility, and usability.”

Proof-of-concept prototypes are built for technical feasibility and can be used to evaluate novel technical approaches.

“Proof-of-concept prototypes are built for this purpose (Tronvoll et al. 2017) and can be used to evaluate novel technical approaches (Fern and Donaldson 1989).”

The scope affects the cost of producing a prototype and the feedback that can be obtained.

“The scope affects the cost of producing a prototype and the feedback that can be obtained (Derboven et al. 2010;Lim et al. 2008;Liu and Khooshabeh 2003;McCurdy et al. 2006;Tronvoll et al. 2017).”

Tronvoll's flexible exploration strategy corresponds to a single exploration strategy where the solution options are based on best-guesses and on facilitating the change of quality requirements as the work progresses.

“Finally, Tronvoll's flexible exploration strategy corresponds to a single exploration strategy where the solution options are based on best-guesses and on facilitating the change of quality requirements as the work progresses.”

The usage environment for a prototype can affect the outcome both in the possible feedback and the representation of subjects in the review.

“The usage environment for a prototype can affect the outcome (Grevet and Gilbert 2015;Lichter et al. 1994;Tronvoll et al. 2017) both in the possible feedback and the representation of subjects in the review.”

We model the exploration strategy aspect using the three facets: single vs parallel exploration, iteration focus, and iteration size.

“We model this aspect using the three facets: single vs parallel exploration, iteration focus, and iteration size These facets are partly based on the four strategies identified by Tronvoll et al., namely point-based, parallel (or set-based solution arrays), optimisation (or performance set investigations), and flexible exploration (Tronvoll et al. 2017).”

Our facet of single exploration corresponds to Tronvoll's point-based strategy where resources are focused on one single solution path and where alternatives are considered before being cemented.

“Our facet of single exploration corresponds to Tronvoll's point-based strategy where resources are focused on one single solution path and where alternatives are considered before being cemented.”

Tronvoll's optimisation exploration uses parallel exploration with a focus on feature or product level, and with gradually decreasing iteration sizes.

“Tronvoll's optimisation exploration uses parallel exploration with a focus on feature or product level, and with gradually decreasing iteration sizes.”

With these four facets of prototype use the main uses of prototype identified in our literature review can be represented, namely internal prototype use without any user presentation, prototype demonstrations, scenario testing, and free testing.

“With these four facets of prototype use the main uses of prototype identified in our literature review can be represented, namely internal prototype use without any user presentation (Budde and Zullighoven 1990;Dow et al. 2011;Schneider 1996), prototype demonstrations (Bellomo et al. 2013;Heisler et al. 1989), scenario testing (Tronvoll et al. 2017), and free testing (Heisler et al. 1989;Tronvoll”

When iterating over multiple parallel prototyping instances, the length of the iterations may impact the extent and quality of the prototyped solution option and thus the prototyping effectiveness.

“When iterating over multiple parallel prototyping instances, the length of the iterations may impact the extent and quality of the prototyped solution option and thus the prototyping effectiveness (Tronvoll et al. 2017).”

In both prototyping in small optimising iterations and managing quality requirements, the outcome focuses on evaluating against a range of values, as opposed to a simple pass/fail, and the increased complexity of needing to consider influencing factors.

“In both cases, the outcome focuses on evaluating against a range of values, as opposed to a simple pass/fail, and the increased complexity of needing to considering influencing factors (Tronvoll et al. 2017).”

Previous research identifies four main strategies, namely point-based, parallel, optimisation and flexible exploration.

“Previous research identifies four main strategies, namely point-based, parallel, optimisation and flexible exploration (Tronvoll et al. 2017).”