Validate Assumptions: Find the Evidence

HOP skills practice • Batch 1, topic 5 of 5. A 5–10 minute toolbox talk plus time for actual field verification. One-page PDF and editable Word talk; separate supervisor and attendance forms.

What is this skill?

Validating assumptions means making an unconfirmed statement visible, identifying the decision that depends on it and obtaining an appropriate basis before treating it as established.

Why use it?

An assumption can pass through several handoffs until it sounds like a fact. Naming the uncertainty helps the right person resolve it before others rely on it.

When should we use it?

Use it during planning, purchasing, handoffs and reviews, especially when someone relies on preliminary information, a previous result or an apparently equivalent replacement.

Where does it apply?

At the planning desk and at the work location. Check that the evidence covers the actual item, revision and conditions; refer technical judgments to the required authority.

Learning objective

Separate one assumption from confirmed facts and identify its validator, evidence and dependent hold point.

Key hazards or failure points

Old evidence used after change; appearance treated as equivalence; confidence replacing a basis; unresolved assumptions lost in handoffs.

How to use it — practical controls

• Write the assumption as a specific statement. Identify what depends on it and what could happen if it is wrong.
• Name the authorized validator, required evidence and deadline before reliance. Hold dependent work when a required condition remains unverified.
• Record the finding and its limits: supported, disproved or unresolved. Carry restrictions into instructions and handoffs; revalidate when relevant conditions change.

Verify It in the Field

• Inspect the evidence's source, revision and scope. Confirm it applies to the actual task. Obtain required technical review; do not invent acceptance margins.
• Paper practice: a mock schedule says Room A is 'probably available.' Identify the assumption, the affected decision and who owns the current availability record.
• Introduce a changed date. Ask whether the previous confirmation still applies. Record the needed evidence and keep the paper decision held until it is supplied.

For real work, record the control, governing source and criterion, safe method, authorized checker, actual result and time. Mark VERIFIED, HOLD/NOT VERIFIED, or N/A with a reason. A practiced skill or matching label does not demonstrate that a physical safeguard functions. Do not create exposure to complete a check.

Stop and reassess

Hold the dependent decision for absent, conflicting, outdated or out-of-scope evidence. Assignment to a reviewer is not closure; a group vote does not establish a technical condition.

Toolbox talk questions

• What are we accepting without enough evidence?
• What fails if that statement is wrong?
• Who can validate it, and what change requires another check?

Examples across different work settings

These are original teaching examples, not operating instructions. Use paper, photographs or inert training items for practice. Change the setting to fit your team while retaining the skill steps and the applicable task requirements.

Office scheduling

Last week's room availability is copied into this week's plan. Confirm the current date and booking with the responsible source before depending on it; a past confirmation has a limited scope.

Procurement or facilities

A replacement looks identical to the previous item. Identify who can establish suitability using approved specifications and manufacturer information. Appearance and a purchase description do not establish technical equivalence.

Field logistics

A route used on the previous visit is assumed to remain available. Obtain current information through the approved planning process and confirm applicable conditions safely. Do not send someone into an uncontrolled area simply to settle the assumption.

Leader follow-through — improve the conditions

Make unresolved assumptions visible in the work package and handoff. Provide access to current information and the necessary technical authority. Avoid performance pressure that rewards marking an open question complete without evidence.

Short supervisor field check

• Assumption is recorded separately from confirmed facts.
• Dependent decision and consequence of being wrong are clear.
• Authorized validator, evidence source and hold point are assigned.
• Actual finding, applicable conditions and limitations are recorded.
• Changed conditions trigger review and restrictions reach the next user.

Use the separate supervisor sheet to retain evidence, open items, correction owner, recheck result and required restart authority. Keep task-specific permits, inspections and technical decisions in their established process.

Attendance and follow-through

Use the separate attendance sheet for participants, roles, questions, actions and rebriefs. Attendance does not establish competence, verify a control or authorize work. Keep completed records private under employer procedures.

Source acknowledgment

Based on DOE-HDBK-1028-2009, Vol. 2 (June 2009). No claim to authorship or copyright ownership of original U.S. Government work. Todd Jerome Jenkins adaptation; no government endorsement implied. Explanations, examples, practice exercises and layouts are original adaptations. Third-party material credited in the handbook retains its original attribution; this notice does not claim rights in that material.

Source file inspected: Volume 2/VOLUME 2 VALIDATE ASSUMPTIONS.pdf; printed pages 22–23. The source concerns scientific and engineering work. This adaptation teaches recognition and referral; it does not authorize workers to set engineering assumptions, ratings, margins or acceptance criteria.

Technical scope and references

References reviewed October 13, 2026. DOE human-performance tools and OSHA recommended practices support preparation and discussion; they do not establish universal technical acceptance criteria. Apply the current task procedure, manufacturer instructions, permit and required competent or qualified decisions. A successful exercise does not replace required training, technical verification or work authorization.

1. DOE-HDBK-1028-2009, Volume 2 — Validate Assumptions, printed pp. 22–23 — June 2009 technical-work guidance adapted to worker recognition and referral. No authorization for workers to make engineering judgments; no generic hands-on check adopted.
2. OSHA Recommended Practices — Hazard Identification and Assessment — Guidance on relevant source information and assessment of changed work conditions.
3. HSE — Procedures — UK regulator guidance on controlled, usable procedures and their limitations; not a U.S. technical acceptance standard.

The DOE handbook is June 2009 illustrative guidance, not a current requirements document. Availability of the official edition and the linked supporting guidance was checked October 13, 2026. Apply current task-specific requirements, manufacturer instructions, permits and required competent or qualified decisions; this talk supplies no universal technical acceptance criteria.

Connect this discussion to your JHA/JSA

Use the JHA/JSA planning and field-verification worksheet to record the actual task steps, hazards, responsible roles and controls. Return to What Changed Today? when the plan or conditions change.

Related Todd Jerome Jenkins articles: How to Conduct a Job Safety Analysis and What Is Human and Organizational Performance?.

Related toolbox talks

• Job-Site Review: Does the Place Match the Plan?
• Questioning in the Field: Notice the Mismatch

Practice another HOP skill

• STAR Self-Checking: Stop, Think, Act, Review
• Peer Checking: Agree Before the Action
• Three-Way Communication: Close the Loop
• Pause When Unsure: Resolve Before Restart

One next step

Use the free JHA/JSA planning and field-verification worksheet linked above to apply this skill to one actual task step. Record what must be checked before exposure and who will check it.