01
Field and Roles
Measuring with numbers what it means to build a product without training a model and to design around uncertain output: the difference and cost of a bare call versus a small scaffolding on the same support ticket task, the number of settings and the boundary of responsibility in the hands of a training approach and a using approach, in how many requests the output changes between two runs of the same input and how much of that the user sees, how much offering options, imposing a format, and grounding narrow the uncertainty, the separation of a measurable capability claim from an unmeasurable general claim, and how many of them can be tied to a test.
- 01 Who Is an AI Engineer Establishing the unit of measurement for building products without training a model: a language model simulator is written and the surface of a given component is read with five numbers. On the same 120 fictional support tickets, a bare call gives 0.5167 label hit rate and 0.3583 unlabeled response share, while a small scaffolding with a label set and a format constraint gives 0.7750 and 0.0000. The cost is written side by side: input tokens rise from 2666 to 6222, output tokens fall from 1648 to 218, the call count rises from 120 to 124, total tokens rise 1.49 times, and the cost per correct label stays near 69 tokens.
- 02 The Difference Between AI Engineering and Machine Learning Engineering Measuring the boundary of responsibility by the number of settings: on the same support ticket problem, two of the training approach's four settings and three of the using approach's four settings (four of five rows once the seed is counted) move the number by more than 0.0200. The training approach asks for 48 labeled examples and reaches 1.0000, while the using approach gives 0.7778 with zero labeled examples. No item of the two setting lists is shared. Retrying moves the number by 0.0139 and adds two calls and 111 tokens, while the seed, which is out of one's hands, moves the number by 0.0417.
- 03 Impact on Product Development Measuring with numbers what it means to design a product around uncertain output: when the same 72 fictional support tickets are called in two runs, on the plain prompt the response text changes in 0.8750 of the records while the decision underneath changes in 0.5972, and in 0.5556 of the records the correct response comes out in only one run. Three design decisions that narrow the uncertainty are measured side by side: imposing a format lowers the visible change from 0.8611 to 0.3056, grounding lowers it to 0.0972 and raises the hit rate to 0.8264 while adding 144 retrieval steps, and offering options raises the change to 0.4306 and doubles the calls.
- 04 The Distinction Between AI and General AI Separating the sentences made about a system by how testable they are: of fourteen fictional claims, five are measurable capability claims and nine are unmeasurable general claims, and one of these carries a number and a direction yet cannot be tested because it has no set. The share that can be tied to a test is 0.3571. Five tests are run on the simulator and four pass: the label hit rate comes out at 0.8264 against a 0.90 threshold and fails, the decision change share passes at 0.0972, the unlabeled response share passes at 0.0139, the document retrieval share passes at 0.9028, and the tokens per request pass at 75.2.