---
title: "PreviewSample"
description: "a representative sample of the units a predicate matched: at most the asked number, spread over the population's strata in proportion with at least one from each stratum that matched, chosen by the hash of the unit so the same predicate gives the same sample"
section: concepts
address: /concepts/previewsample
contract: 0476e35e6e275db5
---

# PreviewSample

a representative sample of the units a predicate matched: at most the asked number, spread over the population's strata in proportion with at least one from each stratum that matched, chosen by the hash of the unit so the same predicate gives the same sample

[figure: PreviewSample is a value at none scope. The drawing shows its fields and the objects that they point at.]

| property | value |
|---|---|
| kind | value |
| scope | none |
| key | none |
| store | none |
| family | rules_engine |



## Fields


| field | type | required | note |
|---|---|---|---|
| `units` | [SampleUnit](/concepts/sampleunit) | yes |  |
| `strata` | [SampleStratum](/concepts/samplestratum) | yes |  |
| `asked` | `count` | yes | the size asked for |
| `method` | `text` | yes | how the sample was drawn |



## Routes that use it
No route takes or returns PreviewSample directly. The record holds it, and the objects that point at it reach it.