Exp Lens Validity Threats

Validity Threats Experimental Design Lens

Philosophical Mode: Adversarial Primary Question: "What alternative explanations survive?" Focus: History Effects, Instrumentation Changes, Selection Effects, Co-interventions, Treatment Diffusion

Arguments

/autoskillit:exp-lens-validity-threats [context_path] [experiment_plan_path]

• context_path (optional positional arg 1) — Absolute path to a lens context file containing IV/DV tables, H0/H1 hypotheses, controlled variables, and success criteria. If provided, read this file before beginning analysis to obtain structured context. If omitted, discover context by exploring the CWD.
• experiment_plan_path (optional positional arg 2) — Absolute path to the full experiment plan. If provided, read for complete experimental methodology and design. If omitted, locate the experiment plan by exploring the CWD.

When to Use

• Quasi-experimental designs without full randomization
• System experiments with environmental changes
• Longitudinal comparisons
• User invokes /autoskillit:exp-lens-validity-threats or /autoskillit:make-experiment-diag validity

Critical Constraints

NEVER:

• Modify any source code files
• Create files outside {{AUTOSKILLIT_TEMP}}/exp-lens-validity-threats/
• Run subagents in the background (run_in_background: true is prohibited)

ALWAYS:

• Apply Campbell & Stanley's full threat taxonomy — do not skip threats just because they seem unlikely

• For every observed difference, enumerate at least 3 alternative explanations

• Assess mitigation strength honestly — "partially mitigated" is better than false confidence

• Distinguish threats that are ruled out by design from those that remain plausible

• BEFORE creating any diagram, LOAD the /autoskillit:mermaid skill using the Skill tool - this is MANDATORY

• If the Skill tool cannot be used (disable-model-invocation) or refuses this invocation, do NOT proceed with diagram creation. Abort this step and omit the diagram from output.

• Write output to {{AUTOSKILLIT_TEMP}}/exp-lens-validity-threats/exp_diag_validity_threats_{YYYY-MM-DD_HHMMSS}.md

• After writing the file, emit the structured output token as literal plain text with no markdown formatting on the token name (the adjudicator performs a regex match):

  diagram_path = /absolute/path/to/{{AUTOSKILLIT_TEMP}}/exp-lens-validity-threats/exp_diag_validity_threats_{...}.md
  

Analysis Workflow

Step 0: Parse optional arguments

If positional arg 1 (context_path) is provided and the file exists, read it to obtain IV/DV tables, H0/H1 hypotheses, controlled variables, and success criteria. If positional arg 2 (experiment_plan_path) is provided and exists, read the experiment plan for full methodology. Use this structured context as the foundation for Steps 1-5; skip the CWD exploration for these fields if the context file supplies them.

Step 1: Launch Parallel Exploration Subagents

Spawn Explore subagents to investigate:

Temporal Changes (History)

• Find system, environment, or data changes during the experiment
• Look for: deploy, release, update, change, migration, incident, outage, rollback

Instrumentation Changes

• Find changes to measurement tools or logging during the experiment
• Look for: logging, monitoring, metric, measure, instrument, version, schema

Selection & Filtering

• Find how subjects, samples, or data were selected
• Look for: filter, select, sample, eligibility, inclusion, exclusion, criteria

Co-interventions

• Find other changes running simultaneously with the treatment
• Look for: concurrent, parallel, simultaneous, co-running, other_experiment, a_b_overlap

Treatment Diffusion

• Find ways treatment effects could spread to control groups
• Look for: contamination, diffusion, spillover, shared, cross, control_exposure

Step 2: Apply Threat Taxonomy

Apply Campbell & Stanley's threat taxonomy: plausibility, design mitigation, mitigation strength → build threat matrix.

Step 3: Analyze Alternative Explanations

For every observed difference: list at least 3 alternative explanations, ruling-out evidence, consistent evidence.

Step 4: Create the Diagram

Direction: TB. Subgraphs: THREAT SOURCES, DESIGN MITIGATIONS, RESIDUAL THREATS

Step 5: Write Output

Write the diagram to: {{AUTOSKILLIT_TEMP}}/exp-lens-validity-threats/exp_diag_validity_threats_{YYYY-MM-DD_HHMMSS}.md (relative to the current working directory)

Campbell-Stanley Checklist

Apply to every experiment:

1. History — concurrent events confounding treatment
2. Maturation — natural changes in subjects over time
3. Testing — pre-test sensitization effects
4. Instrumentation — changes in measurement tools
5. Statistical Regression — regression to the mean
6. Selection — non-random group formation
7. Experimental Mortality — differential dropout
8. Selection-Maturation Interaction — groups maturing at different rates
9. Diffusion of Treatments — control group exposed to treatment
10. Co-interventions — simultaneous competing treatments

Pre-Diagram Checklist

Before creating the diagram, verify:

• LOADED /autoskillit:mermaid skill using the Skill tool
• Using ONLY classDef styles from the mermaid skill (no invented colors)
• Diagram will include a color legend table

Related Skills

• /autoskillit:make-experiment-diag - Parent skill
• /autoskillit:mermaid - MUST BE LOADED before creating diagram
• /autoskillit:exp-lens-causal-assumptions
• /autoskillit:exp-lens-severity-testing