sbtm-reference

Overview

Session-Based Test Management (SBTM) is the dominant framework for managing exploratory testing as a measurable, accountable activity. It was developed by Jonathan Bach + James Bach (1999-2000) and is documented at satisfice.com/sbtm.

The unit of work is a session - a time-boxed (60-90 min) chunk of focused exploratory testing against a mission stated as a charter. Sessions produce session sheets that capture what happened in a structured-enough format for management to aggregate, while leaving room for the tester to learn freely.

This skill is a pure reference consumed by exploratory-charter-author, manual-test-debrief, and the tour-catalogues (exploratory-tours-reference).

For the canonical heuristic catalogs the tester applies during a session, see hiccupps-f-heuristic, sfdpot-heuristic, fcc-cuts-vids-heuristic, crusspic-stmpl-heuristic.

When to use

• Onboarding a tester to SBTM vocabulary.
• Authoring a charter - what fields belong, what mission framing to use.
• Reviewing a session sheet for completeness.
• Building a session-tracking dashboard.

The unit: a session

Per Bach + Bach's SBTM paper (satisfice.com):

"A session is an uninterrupted block of reviewable, chartered test effort... A session may be short (around 60 minutes) or long (up to about 2 hours). Two hours is generally considered the upper limit because tester focus degrades."

Properties of a session:

• Time-boxed: 60-90 minutes typical; absolute upper bound ~2 hours
• Chartered: has a stated mission (what to explore, what to learn)
• Uninterrupted: no context-switching to other work mid-session
• Reviewable: produces a session sheet that the lead can review

The charter

A charter states the mission for one session. Per Bach:

Explore <area>
With <tools / resources>
To discover <information>

Examples:

Charters are not test cases. They state what to investigate and leave the how to the tester's judgment in the session.

A backlog of charters drives multi-session campaigns. The lead prioritises charters per the test strategy (test-strategy-author) and the risk register (risk-matrix).

The session sheet

Each session produces a session sheet. Bach's canonical structure (satisfice.com):

# Session sheet — YYYY-MM-DD — <tester>

## Charter

Explore <area> with <tools> to discover <information>.

## Areas

- (system area 1)
- (system area 2)
- ...

## Session start / duration / setup time / focus

- Started: 14:00
- Duration: 90 min
- Setup time: 10 min
- Charter time: 70 min
- Bug-investigation time: 10 min
- Opportunity time: 0 min

## TBS metrics (time-breakdown)

- Test design + execution: 70%
- Bug investigation + reporting: 11%
- Setup / overhead: 11%
- Opportunity: 0%
- Idle / interruption: 8%

## Data files

- screenshots/2026-05-20-14-15.png
- har/2026-05-20-14-22.har

## Test notes

(narrative of what was tested, in tester's own words; includes
tours applied, heuristics applied, hypotheses formed)

## Bugs (file later)

- B-001: Promo "STACK50" applies after tax instead of before;
  reproduces 3/3. Captured at 14:35.
- B-002: Empty cart + apply promo → page error, not graceful message.

## Issues (meta — testing-process problems)

- Cannot get to step 4 in flow without a paid customer account;
  test data unavailable. Blocking 40% of charter scope.

## PROOF debrief

(See manual-test-debrief)

TBS metrics - time breakdown

Per Bach's SBTM paper, sessions decompose into:

Plus often-included:

• Opportunity: unrelated bugs found by chance; investigated outside charter scope
• Idle: waiting on a build / response

Healthy session: T 60-80%, B 10-20%, S 10-15%. Skewed sessions (T < 50%) signal problems - environment instability, charter too broad, etc.

Dashboard metrics - across sessions

Per Bach's SBTM Reporting paper (satisfice.com), the lead views:

These feed the testing-strategy review at sprint planning.

PROOF debrief

Per manual-test-debrief - the post-session debrief structure:

The lead reviews PROOFs with the tester briefly (5-10 min) before the session sheet is filed.

Common confusions

Anti-patterns

Limitations

• Requires tester skill. SBTM is a framework; it doesn't make bad testers good. The framework's value rises with tester expertise.
• Cadence overhead. Sessions + sheets + reviews add coordination cost. Worth it for medium-+ teams; overhead for solo testers.
• Charter authoring is hard. Vague charters produce vague sessions. Investment in charter discipline pays off.
• Dashboard interpretation requires context. Raw metrics (sessions/week, bugs/session) can mislead without charter-framing context.
• Doesn't replace automated coverage. SBTM is for exploration, not regression - pair with automated suites.

References

• Bach J., Bach J. Session-Based Test Management (2000) - satisfice.com/articles/sbtm.pdf.
• Bach J. Exploratory Testing Explained - satisfice.com/articles/et-article.pdf.
• Bolton M. Exploratory testing series - developsense.com.
• Hendrickson E. Explore It! (Pragmatic Bookshelf, 2013) - book.
• Sibling references (heuristic catalogues the session applies): hiccupps-f-heuristic, sfdpot-heuristic, fcc-cuts-vids-heuristic, crusspic-stmpl-heuristic, exploratory-tours-reference.
• Consumed by: exploratory-charter-author, manual-test-debrief.