Once you have a variety of potential solutions/designs how do you know which one(s) to choose to iterate on and which ones to discard?
The ideal concept is something you can make without too much difficulty, delivers the intended benefit, is intelligible, leaves you open to future improvement, and has a ready way of witnessing success.
Typically you’ll be working on a team with (or at least have a high level of contact with) someone in charge of the product (a product manager, usually) and someone in charge of engineering (a software architect or software engineer, usually) – with design this group forms the “product trio.” Each person on the trio has expertise in or evidence for some of the criteria by which you might evaluate concepts. With these in mind the negotiation of which concept (or what parts of which concepts) can begin. For example:
UX – Is this concept intelligible to users, i.e. do they understand it and believe that it will deliver the desired benefit? Will this concept create a pleasant experience for the people we hope to serve? Does this concept use familiar interaction paradigms? Is this a concept we can build on later or will it need to be scrapped to add functionality? Can we partialize this concept if we need to reduce scope? Will we be able to detect whether or not people are successful in using it (e.g. by counting orders or conversions of some kind, or some other measure of user outcome)? Etc.
Product – will this concept deliver the intended benefit? Is this concept strategically relevant? Does the cost/complexity fit our appetite to do the work? Does it seem intelligible to customers (who might be distinct from users)? Can we partialize this concept if we need to reduce scope? Can we add capabilities to this concept to improve it in the future? Will we be able to detect whether or not use of the concept is helping the business (e.g. by counting orders or conversions of some kind, or some other measure of business outcome)? Etc.
Engineering – is this concept feasible? Does it use data we have available or can get readily? Does it use technology and services we are familiar with or can learn readily? Does the cost/complexity fit our appetite to do the work? Does it lead us into an area we want to develop technically or to strengthen existing capabilities? Etc.
You can see some overlap. For example, the appetite question is PM + Engineering, for example. Customer and user intelligibility is PM + UX. There are others.
In an individual case study lacking these team members you will need to guess at some of these, or at least reveal your thinking about your concept selection.