What makes a good case study?

Most case studies are written to flatter the supplier and read as advertisements, which is why they are skipped. The ones that work do something different: they let a reader recognise their own situation in the opening lines and then show, in checkable detail, what happened. Recognition first, evidence second, and the supplier's competence emerges from the account rather than being asserted in it.

Recognition means the situation has to be specific. The size of the business, the sector, the constraint they were under, what they had already tried and why it had not worked. A reader scanning for whether this is relevant makes that judgement in seconds, and a generic opening about a client in the manufacturing sector who wanted to improve efficiency fails it immediately. The details that make it recognisable are the same ones a nervous supplier removes for confidentiality, which is where most case studies lose their value.

Evidence means figures that could be disputed. A before and a after, with the period stated and the measurement named. Where a figure cannot be published, the honest move is to say what was measured and why the number is withheld, which is more credible than an unattributed percentage. Round improbable percentages with no baseline are read as marketing by exactly the buyers you want, because those buyers have written some themselves.

The element that most distinguishes a credible case study is an account of what was difficult. What did not work, what took longer than expected, what the client had to do that was inconvenient, where the approach had to change. Including it costs nothing in perceived competence — problems are expected — and it does more for credibility than any result, because it demonstrates that the account is a description rather than a construction.

Length should follow the reader rather than the project. The people who read case studies fully are usually already interested, and the ones scanning need the situation, the outcome and the figures near the top. Putting the result in the first paragraph and the detail below serves both, and it also means anything extracting from the page finds the substance rather than a preamble.

One practical note that determines whether these get written at all: capture the material at the time. The specifics that make a case study useful — what the constraint was, what was tried, what the numbers were before — are hard to reconstruct months later and easy to note during the work. Businesses that decide to write case studies retrospectively usually produce vague ones, because vagueness is all the surviving record supports.