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Experimentation

As explained in Causal AI

An A/B test is an experiment that compares outcomes under two assigned variants, commonly labeled A and B.

When a product team asks whether changing game dynamics increases purchases, correlation from existing player data cannot answer the intervention question reliably. An A/B test assigns people to variants, applies the alternatives, and compares outcomes under controlled conditions. section 7.1.4 section 7.1.5

A practical experiment separates the intervention from the measurement:

  • Select a population and randomly assign participants to two groups. section 7.1.5
  • Fix the treatment condition for each group, such as low versus high side-quest engagement. section 7.1.5
  • Measure the same outcome for both groups and compare their means. section 7.1.5
  • Test whether the observed difference is statistically significant, while recognizing that running the experiment can impose opportunity costs. section 7.1.5

Game-dynamics experiment

Assign 1,000 players evenly to low- and high-engagement variants. The low group averages $92.99 in purchases and the high group $131.38, a difference of $38.39; the corresponding test treats the difference as significant. The result supports evaluating the policy through randomized assignment rather than observational association. section 7.1.5

Table 7.3 Example rows from the experimental data evaluating the effect of Side-Quest Engagement on In-Game Purchases
User ID
Side-Quest Engagement
In-Game Purchases
2828924d
low
224.39
7e7c2452
low
19.89
3ddf2915
low
221.26
10c3d883
high
93.21
c5080957
high
61.82
241c8fcf
high
188.76

Inspect example experimental rows showing assigned conditions alongside observed purchase outcomes. section 7.1.5

Randomized experiments are often more robust to mistaken causal assumptions than simulations, but infeasible, unethical, or impossible interventions require causal-model simulation instead. Real experiments can also create attrition, spillover, missing-data, or post-randomization-confounding problems. section 7.6.1 section 11.1

How Causal AI covers it

How deep it goes
Explains assignment, intervention, group means, significance testing, costs, and causal complications, but defers detailed experimental diagnostics.
Examples
Uses an online game, side-quest engagement variants, in-game purchases, summary statistics, and a Python significance test.
What you can do after
Apply via Python by comparing randomized groups, summarizing outcomes, and testing their mean difference.
How it connects
Connects randomized experiments to interventions, causal inference, treatment effects, confounding, and average treatment effects.

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This explainer was generated by Manning's knowledge graph from the text of Causal AI. The section links point to the parts of the book it draws on.