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Output variance

As explained in Prompt Engineering in Practice

Output variability is the degree to which generated outputs differ across generations for the same task.

Output variance is the degree to which generations differ for the same task. When results are inconsistent, treat the variation as a diagnostic signal: check whether the prompt leaves room for multiple valid interpretations before blaming the model or API. section 1.6.3 section 8.1.1

Use these checks to locate and manage variability:

  • Look for underspecification. Add an output schema, constraint, or worked example to narrow the prompt’s possible interpretations. section 1.6.3
  • Consider sampling settings as a separate cause. Temperature 0 minimizes variability; moderate temperature permits useful variation, while very high temperature can increase noise. section 8.1.1

Support-ticket classification

If classification works when tickets use internal feature names but varies when users describe features informally, add a mapping from common descriptions to the internal taxonomy. This closes an interpretive gap in the prompt. section 1.6.3

How Prompt Engineering in Practice covers it

How deep it goes
Explains prompt ambiguity and temperature as causes of variability, but does not define a numerical measurement method.
Examples
Uses support-ticket classification with informal feature descriptions and contrasts temperature settings from zero to high.
What it assumes
Assumes professional software-engineering familiarity but no machine-learning background; chat-interface experience is sufficient.
What you can do after
Diagnose inconsistent generations by tightening prompt specifications and considering sampling settings as a separate source of variation.
How it connects
Connects output variance to prompt underspecification, output schemas, constraints, worked examples, temperature, and sampling.

Related concepts

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