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Lesson 7 of 7 · 50 min

Deliver a reproducible exploratory evidence pack

Learn the reasoning. Try the task. Compare your answer.

Prepared for DataCareerHub · Curriculum version 2026-10-15.4

By the end of this lesson

  • Combine preparation, summaries and graphics into a coherent analysis.
  • Write findings with scope, sensitivity and limitations.
  • Use a practical rubric to identify remaining analytical gaps.

April–May teaching extract · Order values in EUR · Delivery blanks remain missing · Use a local spreadsheet; Python is optional.

Understand the method

An exploratory analysis is complete when another person can understand what you inspected, reproduce the key results and see how strongly the evidence supports your proposed action. A folder of charts and a long list of metrics is not enough. Organise the work around Northstar’s question: does this supplied extract justify scaling the initiative? Your answer should explain the observed change, the conditions that affect it and what evidence is still needed.

Build a small evidence pack

Keep the untouched raw extract, your prepared analytical copy, the quality log and an analysis worksheet or script. Add a scope note defining one-order grain, April–May dates, EUR units and completed-status eligibility. Include a row bridge from 46 records to 44 verified orders and then 40 completed orders. This bridge helps a reviewer trace inclusion decisions before reading a monetary result.

Your monthly summary should contain count, total value, AOV and median. Your channel table should reconcile to the monthly counts and values, show the order shares and disclose sparse groups. A separate delivery table should show measured and eligible counts alongside averages. Keep actual results separate from the equal-mix and outlier-exclusion scenarios. The same label should never refer to two populations.

Choose graphics that answer a question

For distribution, create the five-bin frequency chart from Lesson 4. State the interval boundaries and counts so the chart is reproducible. Keep the €1,000 order represented. For composition, use grouped columns showing April and May AOV for web, store and the overall population, or a small multiple with a common EUR axis. Include group counts in the adjacent table. A second chart of channel order shares can help explain the changing weights.

Use a zero baseline for value bars, clear month labels and a restrained colour pair consistent across charts. Provide the numeric table and a text description so colour is not the only source of meaning. Do not combine order counts and EUR on a single unlabeled scale. A two-month teaching extract does not establish a seasonal pattern or a stable trend; avoid adding a forecast line to make the graphic feel more sophisticated.

Write a decision note

In 120–180 words, state the scope, observed change, major interpretation issue, data-quality treatment, coverage limitation and next evidence-gathering action. Name counts and denominators where they influence the conclusion. Explain that the store baseline has two orders and contains A020 at €1,000. Keep the legitimate order in the baseline and label any exclusion scenario. Do not invent an advertising return, a profit estimate or a causal effect from the supplied fields.

Check reproducibility and boundaries

Reopen your files and repeat the calculations from your prepared inputs. Compare your monthly and channel outputs with the downloadable results after attempting the exercises. If using the optional Python worked analysis, read its comments and run it on a local practice copy; it does not require third-party packages, credentials or a website connection. It validates inputs and prints JSON without modifying the practice files.

The rubric supports self-review rather than an accredited assessment. A concise analysis with explicit uncertainty is stronger than a confident recommendation built on an unsupported metric. Your final action may be to collect comparable periods, verify the channel-mix explanation and obtain cost information before any expansion decision. That is a practical analytical outcome even when the answer is not “scale now.”

Your turn

Practical exercise

Complete the evidence pack: raw and prepared data, quality log, scope note, row bridge, monthly metrics, reconciled channel table, distribution chart, coverage table and a 120–180 word decision note. Include one labelled sensitivity comparison and identify a next investigation. Use the ten-point rubric below to review your own work.

Rubric: preparation/provenance 0–2; population and calculations 0–2; segment weights and sensitivity 0–2; missingness and denominators 0–2; communication and reproducibility 0–2. Award two when complete and correct, one when present but incomplete, and zero when missing or materially wrong. Aim for eight or more, with no zero in calculations or provenance. Keep unsupported causal claims out of the final note.

Open the worked solution

Worked decision note

In the supplied April–May 2026 extract, completed-order value increased from €2,900 to €3,420, or 17.9%, with 20 completed orders in each month. Overall AOV rose from €145 to €171, but web AOV fell from €100 to €90 and store AOV from €550 to €180. Store’s order share changed from 10% to 90%. April’s store baseline has only two orders and includes verified order A020 at €1,000, so the comparison is sensitive to composition and a large order. The prepared dataset resolves two excess records and six field issues using declared rules or the supplied reference. Delivery means describe only 14/20 April and 19/20 May completed orders; the missing observations prevent an all-order service claim. Retain the verified large order in baseline results and report exclusions separately. Obtain comparable periods, channel-context evidence and costs before using this sample to justify expansion; it does not establish profitability or causation.

Review the supporting evidence

The monthly and channel result files should reconcile exactly to your prepared data. Show the 44 retained IDs, 40 completed orders, €6,320 combined baseline, €158 combined mean and €110 median. The optional worked script checks these relationships and prints the sensitivity and coverage calculations. Its assertions detect this fixture’s documented defects; they are not a general-purpose production cleaning service.

A complete submission earns two points in each rubric category. If the counts match but Y007’s channel was chosen arbitrarily, preparation/provenance is not complete. If the totals match but delivery blanks were filled with zeros, missingness/denominators is materially wrong. If a graphic omits group counts and claims the initiative caused growth, communication needs revision. Use a changed input on a disposable copy to check that your calculations update or fail clearly rather than continuing to display a cached answer.

Check your understanding

One more question.

Which recommendation is supported by this exploratory extract?

Practice feedback only. This check is not a graded assessment and is not saved.

Method references: NIST exploratory data analysis and box plots and IQR fences. The case and exercises are authored for DataCareerHub; the quartile convention is stated in the dictionary.

How these learning materials are prepared and maintained · Report a correction: support@datacareerhub.io

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