Week 4: Metric Design and Business Outcome Linkage · Lesson 4.4

Segmentation strategy for AI systems

Where does the system work well, where does it fail, and how do we structure segments to see it?

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Free, self-paced. Read the deck with its speaker notes, work the practice from the slides, then take the week's quiz for a certificate.

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Speaker notes

Welcome back. So far this week you've classified your metrics, picked a measurement pattern for each part of the AI Data Analyst, and worked out how to afford running the evals. All of that produces numbers, usually one number per metric. Today is about what one number can hide. An overall SQL correctness rate squeezes every kind of user and every kind of question into a single figure. The math is fine. The problem is that the average can look healthy while one group of users is getting a badly broken product. So today you'll learn to break a metric down by the groups that matter, check how much you can trust each group's number, and decide which group to fix first when you can't fix everything. What you'll end up with is a ranked list of segments you can bring into a launch meeting. The question to keep asking all lesson is short: this number is good for whom?

About this lesson

The AI Data Analyst’s SQL correctness is 86 percent, just above its 85 percent threshold, so the team ramps it to half of its users. Days later the complaints start. The number was right. It was an average, and the easy queries that make up most of the traffic were carrying it.

This lesson is about breaking one metric into the groups that matter: query complexity, domain, user role, or anything else you can see before the system answers. Splitting by whether the query succeeded doesn’t count, because that only restates the metric. For each segment you report the rate, the sample size and a confidence interval, and you flag any segment with fewer than 20 traces as too small to act on alone.

Then you rank what you found by volume times severity. Big segments with real problems come first, and safety-critical segments like finance get pulled up the list even when they’re small.

In the worked example you predict what a split by query complexity will show, then look at the segment rates and their intervals. One segment turns out to be badly broken, and its interval is so wide that the first step is collecting more traces before sizing the fix.

In the practice you rank four segments by volume times severity, one of them too small to act on, then check your ranking against ours. You pick three dimensions for your own product and assemble a segment prioritization schema that feeds the release criteria in 4.6. On the extended track you work out how much each segment adds to the average, design a dimension you’d derive from the raw trace, and see how few traces are left when you combine two dimensions.

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