Rethinking a negotiation tool for two purchasing roles.
Study purchasing teams’ working practices, synthesise their needs and propose priorities to guide the design of a working prototype.
This account describes my approach. The project’s interfaces, data and internal documents are not presented.
Start with purchasing teams’ actual work
The Should Cost Model is a negotiation support tool for a retail group’s purchasing teams. It serves two roles: buying products sold under the retailer’s own brand and negotiating products from manufacturers’ brands. The research aimed to understand the existing application’s limitations and the needs of teams that did not yet use it.
I prepared a protocol adapted to current and prospective users: 45–60 minute remote interviews about their roles, working practices and difficulties. With current users, I observed their natural use of the tool, followed by a critical debrief. For the other group, the interview included an introduction to the application to discuss its relevance and their needs.
I then synthesised uses, difficulties and needs for each purchasing role. Interviews showed how teams prepared negotiation arguments and supplemented their analyses in spreadsheets. The review distinguished data problems, missing features and interface improvements: these findings called for different responses.
Turn findings into design priorities
A shared need emerged: see the purchasing portfolio before exploring individual products. The existing tool focused on product detail. The synthesis also identified needs for comparison and tracking changes over time, with differences between the two roles.
I grouped requests into a shared list, then prepared priorities for each team. An overview and the ability to move between levels of analysis were among the first topics to address. The RICE framework helped discuss this order: people affected, expected benefit, confidence in the estimate and effort required. These were prioritisation assumptions.
The Product Review I prepared made the reasoning traceable: observations → needs → proposals → priorities for discussion. It provided a framework for the next steps: validating priorities with each team, preparing mockups, then refining them with users in co-design workshops.
Make it clear what the user is looking at
Screen feedback called for clearer reference points: which products, which period and which comparison? It also raised questions about the information available and its reliability.
My takeaway is that two tasks need attention: making the screen understandable and checking the data with the business experts responsible for it. Understanding the information before using it to make a decision becomes a criterion for assessing proposals.
Turn journeys into something people can use
I built a working React and TypeScript prototype with AI assistance. People can follow a sequence of actions, change context and find information along a journey. This gives users and developers a concrete basis for discussing the expected behaviour.
My role covers research, experience design and building the prototype. The business analysis model predated the engagement. The deliverable presented here is a design prototype; a production release and benefits in use are not documented in this account.
« I had the pleasure of working with Vianney for 6 months within the "Offer & Negotiation" North Star on the Should Cost Model project.
Vianney stood out for his ability to grasp complex business challenges very quickly, spanning own-brand buyers and negotiators at major European buying centres. His contribution was instrumental in three areas:
1/ Synthesis and Vision: He carried out a thorough, structured synthesis of user needs, helping bring together two traditionally different worlds (national brands and own brands) within a single interface.
2/ Quality of Execution: A constant source of proposals, Vianney delivers prototypes of high visual and technical quality, with a "dev-ready" level of finish that greatly facilitates the development teams’ work.
3/ Agility and Humility: I particularly appreciated his adaptability. Vianney knows how to challenge his own proposals to incorporate key additional features identified following user workshops.
Beyond his expertise as a Designer, Vianney has a thorough command of agile ways of working and navigates complex organisations involving many stakeholders with ease. I highly recommend Vianney for any product design project that demands rigour and a strong user-centred vision. »