Write a case study that connects evidence to a recommendation

Understand the method

A case study turns project artefacts into an explanation a reviewer can follow. Begin with the question and the practical decision, not a list of software features. Then describe the source and preparation, the method, the material findings, the limitations and the next action. Keep the narrative selective: each section should explain a decision you made or evidence that affects the conclusion.

Describe the source and method

State that the project uses fictional DataCareerHub Northstar data and is guided practice. The April–May extract contains 46 raw records and 44 verified orders, with 40 completed orders in the headline analysis. Explain the two excess records, six field corrections and remaining missing delivery measurements. Link the detailed log instead of burying the reader in every source row.

Name your primary tool and the calculation route. The SQL route can identify P3/P4 for monthly and channel summaries, P6 for the observed-period comparison and P8 for the labelled exclusion scenario. A spreadsheet route should identify its input table and summary references. Do not list a tool as used merely because an optional reference file was provided. Traceability is more persuasive than a long technology inventory.

Lead with the material finding

Completed value rises from €2,900 to €3,420 with 20 orders each month, so AOV rises from €145 to €171. Both channel AOVs fall while store’s order share changes from 10% to 90%. April store has only two orders and includes the verified €1,000 A020 record. These facts explain why the aggregate alone is insufficient evidence for expansion.

Keep measures and comparison language precise. The completed-value change is 17.9%; the store-share change is 80 percentage points. Delivery means are observed-only averages with unequal coverage. Avoid a sentence such as “The initiative increased profit by 18% and improved delivery,” because profit, causation and all-order service improvement have not been established.

Make the recommendation proportionate

Recommend investigating the channel-mix change, collecting comparable periods and obtaining costs before deciding to expand. Name what that evidence would help assess. The report need not settle an unsupported business question to be useful. It should make the next investigation more focused and prevent the reader from treating a descriptive increase as a proven commercial effect.

Keep the evidence close

Use a summary table or a chart with exact values, a compact data-quality section and links to the analysis and dashboard. Provide a 120–180 word decision note that can stand alone with its population, key context and limitation. The downloadable worked_portfolio.html illustrates this structure and includes a clearly marked guided-contribution section. Its professional appearance is a communication aid, not a substitute for independent work.

Finally, check each claim against a query or worksheet result. If a number cannot be traced, either supply the method or remove the claim. If a conclusion depends on a scenario, label that scenario at the point of use. This makes the case study an auditable account of reasoning rather than a narrative written after choosing a preferred answer.