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Large Language Models (LLMs) are probabilistic; the same prompt can yield different outputs across runs. This variability makes it hard to tell if a change truly improves performance or is just random noise. Repetitions help address this by running the same input multiple times, reducing uncertainty and revealing stable patterns. In evals, repetitions ensure metrics are more reliable, comparisons between experiments are meaningful, and improvements can be validated with confidence.
This guide walks through how to:
  • Generate a dataset of synthetic customer reviews
  • Upload them into Phoenix
  • Run experiments that capture repetition patterns
  • Compare how repetitions impact evaluations across experiment runs
Along the way, we’ll show both code snippets and Phoenix UI screenshots to demonstrate the full workflow.

Notebook Walkthrough

Running Experiments with Repetitions

View the complete notebook on GitHub

Create Synthetic Customer Review Data

Upload as a Dataset in Phoenix

Dataset view showing customer reviews

Define Evaluation Task as the Experiment to Run

Run Experiment!

Experiment view showing repetition results