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Lesson 4 of 5 · 50 min

Request the evidence and plan quality checks

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

Prepared for DataCareerHub · Curriculum version 2026-10-15.1

By the end of this lesson

  • Map questions to fields and identify unavailable evidence.
  • Specify quality tests and actions before analysis.
  • Request the minimum necessary data without exposing customer content.

Harbor Helpdesk · UTC · Snapshot 22 June 2026 00:00 · Prepared fictional extract · No Python or SQL required.

Understand the method

A data request should explain why each field is needed. “Send everything” increases handling risk and still may omit the one field required to answer the question. Build an evidence inventory: question, required field, available source, grain, owner, expected coverage and action if unavailable. Separate the supplied teaching facts from data you propose to obtain in a real evaluation.

Start with available evidence

The ticket file supplies a unique ticket key, creation and response timestamps, first-resolution timestamp, channel, queue, priority, snapshot status and optional satisfaction. It can support descriptive response timeliness, a mature first-resolution guardrail and respondent-only rating summaries. It cannot show routing exposure, agent workload, paid hours, ticket complexity in detail, reopen history or the true arrival volume of the business. The case notes describe concurrent changes; they are not a row-level assignment log.

Request a dated routing deployment/exposure log if the stakeholder wants an intervention comparison. Ask for staffing and staffed-hours records to understand capacity, plus a longer consistently instrumented baseline and follow-up. A proposed request might cover four comparable weeks before and four after, subject to availability and seasonal context. That is a planning proposal, not evidence that four weeks is sufficient for a powered causal study. A randomized or carefully designed evaluation needs separate feasibility and methodological review.

Specify checks and decisions

For ticket_id, test nonblank uniqueness. If duplicate keys appear, compare records and request authoritative resolution; do not simply keep the first row. For timestamps, test parsing, UTC interpretation, creation within scope, response/resolution not before creation and recorded events no later than the snapshot. For categories, check channel, queue, priority and status against documented allowed values. Count missing values by field and cohort. Reconcile retained records to source records and test outcome maturity.

Each check needs an action. A malformed creation timestamp prevents cohort assignment: quarantine it with a reason and obtain correction. A missing rating does not invalidate a response-time calculation: retain the ticket and exclude the blank only from the respondent-rating denominator. A missing first resolution on a mature ticket is legitimate in this case, where the dictionary defines it as no first resolution recorded by the snapshot. Do not fill it with the snapshot date or claim it was resolved.

The supplied file is intentionally a prepared, internally consistent extract. There are 24 unique ticket keys, 24 observed first responses, six blank first resolutions and eight blank ratings. Those blanks are documented conditions, not deliberate defects to “clean away.” Your task is to write checks and interpret their meaning, not to manufacture a cleaning story.

Keep access proportionate

This exercise contains no names, email addresses or message text. A real response-time analysis usually needs event timings and stable pseudonymous ticket keys, not full customer conversations. Explain the purpose to the data owner, request the minimum necessary fields, agree approved storage/access and a retention period through the organization's process, and avoid sending confidential files through a public enquiry form. These are planning considerations; this course does not certify legal compliance.

Finish with a readiness decision: proceed with a bounded descriptive comparison, pause an unsupported calculation, or ask for a missing dependency. An honest “we can describe the extract, but cannot attribute the change” is a useful outcome. Log unresolved definitions and obtain stakeholder review before moving into a more expensive analysis.

Your turn

Practical exercise

Use the data inventory section in analysis_plan_template.txt. Map five analytical needs to fields or unavailable sources. Write six quality checks with a pass condition and failure action.

  1. Count blank resolution timestamps and ratings; explain whether each requires deletion.
  2. List three missing sources needed to evaluate routing more credibly.
  3. Rewrite “send all customer conversations” as a proportionate request.
  4. State the strongest analysis that can proceed with the current file.
Open the worked solution

Inventory: cohort → created_at_utc; timeliness → creation/first response; guardrail → creation/first resolution plus snapshot; mix → channel; satisfaction context → optional rating and coverage. Routing exposure, staffing hours and longer baseline are unavailable requests, not imputed columns.

Checks/actions: unique nonblank key → investigate duplicates; parsed UTC dates → quarantine malformed rows; creation in window → count exclusions; nonnegative response/resolution durations → investigate invalid events; events ≤ snapshot and mature eligibility → separate unobserved/immature outcomes; categories in dictionary and ratings 1–5 → flag unexpected values. For every action keep source rows and record the reason.

Six blank resolutions are mature tickets with no first resolution recorded; retain them in the guardrail denominator. Eight blank ratings are missing observations; retain tickets for other metrics and report respondent coverage. No row deletion follows automatically. Request pseudonymous ticket events, channel/queue, relevant exposure and staffing aggregates via approved access, not names or conversations by default. A bounded descriptive cohort/channel comparison can proceed; an attributable routing-effect or productivity estimate cannot.

Check your understanding

One more question.

What should happen to a ticket with a blank satisfaction rating?

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

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Harbor Helpdesk is a fictional teaching case. Descriptive comparisons do not establish routing causality. Portfolio practice is not a claim of client work or an accredited qualification. Explore practical lessons, worked examples and projects. Follow a published path, practise the method and build work you can explain.