"Write a case study" — the prompt that produces a testimonial, not evidence
Why an open case-study prompt returns vague praise instead of a result, and the rewritten version built around a measurable before and after.
The prompt, as typed
Write a case study about one of our customers. Make it compelling and professional.
What it leaves the model to guess
- The measurable before and after
- Which objection the case study is meant to answer
- Who reads it and at what stage
- Length, structure and what cannot be claimed
Graded before and after
Both versions below were scored by the same rubric the free prompt grader runs.
As typed
8/100 · grade F
| Clarity of context | 0 |
|---|---|
| Structure | 0 |
| Specificity | 2 |
| Reusability | 0 |
| Decision logic | 0 |
Rewritten
90/100 · grade A-
| Clarity of context | 8 +8 |
|---|---|
| Structure | 10 +10 |
| Specificity | 8 +6 |
| Reusability | 6 +6 |
| Decision logic | 5 +5 |
The rewritten prompt
Write a customer case study for {{audience}} at the {{funnel_stage}} stage.
Customer: {{customer}} — {{customer_context}}
Situation before: {{before_state}}
What changed: {{intervention}}
Measured result: {{measured_result}}
Objection this case study must answer: {{main_objection}}
Tone: {{tone}}. Channel: {{channel}}.
Output, 550-700 words:
- Headline stating the result, max 12 words
- Situation section: the before state in the customer's terms
- What changed: what was actually done, in order
- Result: the measured outcome, with the number stated once and not repeated
- One pull quote of no more than 25 words
Constraints: no claim that is not supported by {{measured_result}}. No
"partnered with", "seamless", "excited to announce". Do not describe the
result as "significant" — state it.
Write 3 headline options and rank them by how directly the result answers
{{main_objection}}, with one line explaining the top pick.
The case study succeeds if a sceptical reader can say what changed, by how
much, and over what period. Check the draft against that test before finishing. Why the rewrite works
Most case-study prompts produce praise because nothing in them requires evidence. Naming the before state, the intervention and a measured result turns the model's job from describing a relationship into reporting a change — and the final check gives it a test it can actually apply.
Common questions
- Why does this prompt score badly?
- It scores 8 out of 100 (F) because it leaves the model to decide 4 things you already know: the measurable before and after; which objection the case study is meant to answer; who reads it and at what stage; length, structure and what cannot be claimed.
- Does a longer prompt always score higher?
- No. The rubric rewards named inputs, a fixed output format and an explicit rule for choosing between options. Extra prose without those adds length and no score.
- Will this rewritten prompt work in ChatGPT and Claude?
- Yes. It is plain text with placeholders you fill in before running, so nothing in it is specific to one model or vendor.