Choose the axis
Identify the single experimental factor you want to vary while holding the rest of the setup as stable as practical.
Alpha 1 · Single-axis diagnostic
Just a Marble
A test-axis witness for experimental design.
Just a Marble helps test whether changing an experimental axis produces meaningfully new information.
Experimental, advisory, and early-stage. It does not establish causation, statistical significance, or production readiness.
condition A
condition B
Change one axis. Observe whether the selected metric changes with it.
What it does
A controlled comparison, not a verdict.
Every result is shaped by the experiment you supply: the axis, runner, metric extractor, conditions, and sample design.
Provide the experiment
Supply a runner that executes each condition and a metric extractor that converts each run into a comparable result.
Compare the structure
Just a Marble runs controlled variations and checks whether the selected metric separates the axis conditions.
Read the advisory label
The output is an MDC classification: a compact indication of how much distinguishable information appeared under the supplied design.
How it works
One axis. Five explicit steps.
- 1 Define the test axis Name the controlled factor being changed.
- 2 Run controlled variations Execute each condition through the supplied runner.
- 3 Extract a metric Reduce each run to the feature you chose to observe.
- 4 Compare outcome structure Look for separation, overlap, or weak distinction.
- 5 Return a classification Report an advisory MDC label with supporting output.
Current labels
MDC classification
The labels describe the observed distinction produced by the supplied experiment and metric. They do not certify the experiment, prove an effect, or replace statistical analysis.
MARBLE
The selected metric does not meaningfully distinguish the tested axis conditions in the supplied runs.
LOW_MDC
The metric begins to show condition-sensitive structure, but the distinction remains limited or weak.
MODERATE_MDC
The outcome structure shows a clearer relationship to the tested axis under the current design.
HIGH_MDC
The supplied metric strongly distinguishes the tested conditions within the current experiment and sample design.
Interpretation boundary:
Classification quality depends on the runner, metric, conditions, sample count, and controls provided by the user.
Alpha 1 examples
The metric decides what the experiment can see.
Random walk · completion only
Same axis, non-sensitive metric
axis = step_size
metric = run_completed
result = MARBLE
Step size changes, but the extractor records only whether each run completed. Because completion does not distinguish the conditions, the output is MARBLE.
Random walk · maximum excursion
Same axis, axis-sensitive metric
axis = step_size
metric = max_abs_position
result = LOW_MDC
Maximum absolute position can respond to step size. The metric begins to separate the conditions, producing an advisory LOW_MDC classification.
Current release state
Alpha 1
A compact Python reference implementation for independently running a single-axis diagnostic experiment.
- ImplementationSingle-axis Python reference
- Test status26 standalone tests passing
- RoleAdvisory diagnostic tool
- Statistical claimNot statistical proof
- CertificationNot production certified
- CLINot yet available
- Multi-axis modeNot yet available
- Package releaseNot yet available
License summary
Source-available, not open source.
This summary is for orientation only. The full license text controls if any wording differs.
Request commercial licensingAllowed without a commercial license
- Personal use
- Teaching and internal noncommercial academic research at accredited universities and colleges
- Genuinely free, noncommercial games or tools created and publicly shared by individuals
- Private modification by otherwise permitted users
- Publication of research results
Requires written permission or a paid license
- Business, nonprofit, government, or contractor use
- Sponsored work or client work
- Revenue-generating use
- Redistribution of JAM source code or modified forks
Built using Just a Marble by Stephen Montgomery
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