---
title: "Comparable Sales Small Samples: What a Median Can and Cannot Say"
description: "Read a comparable-sales median with its sample size, dates, missing fields and product definition. Compare individual observations before using a sparse market result."
author: Yan Zhu
date: 2026-10-09
dateModified: 2026-10-09
language: en-AU
category: Guides
url: https://premiumrea.com.au/blog/comparable-sales-small-sample-median
tags: ["Property evidence", "Market research methods", "Development research"]
---

# Comparable Sales Small Samples: What a Median Can and Cannot Say

*By Yan Zhu, Co-Founder & Chief Data Officer at PremiumRea — 2026-10-09*

> Read a comparable-sales median with its sample size, dates, missing fields and product definition. Compare individual observations before using a sparse market result.

## Put the sample beside the statistic

A comparable-sales small-sample median summarises the observations selected, not every property in the market. Show the number of qualifying sale events, the period covered, the location rule and the target product. If only one observation qualifies, the displayed median is simply that sale’s price. Its presence does not establish a stable price level or a forecast for another property.

## Inspect each observation first

Check price source, contract date, built form, configuration, condition, title and whether the asset was completed at sale. CAV’s pricing guidance refers to similar properties.[1] A median can conceal important differences when the sample is sparse. Keep the individual comparison sheet available so a buyer can see which records are genuinely close and which only provide background.

## Explain the effect of missing data

A narrow filter can remove records whose bathroom count, built form or sale price is unknown. The remaining sample may favour newer, more actively marketed or better-described properties. List the missing categories and the known coverage limitations. No disclosed price is not a zero-price sale; no qualifying result is not proof that no relevant property traded.

## Separate repeated trades from separate properties

A single property may sell more than once during the period. Preserve distinct transactions when studying prices, but do not call the event count a count of unique buildings. For a development comparison, inspect whether the product changed between those events. A later completed sale and an earlier land sale should not enter the same product set merely because the address matches.

## Use sensitivity checks without changing the question

Compare the strict product set with a clearly labelled broader set, then explain the change in inclusion rules. Test the effect of excluding a known outlier or changing the period, but retain the original result. Do not widen the filter only until it produces a preferred number. Differences across sets are information about uncertainty, rather than permission to select the most optimistic value.

## Keep the acquisition decision conditional

A sparse result can justify further inspection or a request for additional evidence. It cannot substitute for property-specific valuation, legal review or a fully scoped project budget. Present the range of supported observations and the unresolved assumptions together. Where close matches are unavailable, describe the evidence gap rather than calculating an unsupported precision adjustment.

## Questions buyers ask

### Does a one-sale median estimate the market reliably?
It describes one selected sale. Its relevance depends on product similarity and the evidence available.

### Should unknown-price sales be treated as zero?
No. Keep the missing price separate and disclose the resulting coverage limitation.

## Continue the evidence check

Use the [development evidence hub](/development-evidence) to build a source-linked issue register, then compare the [Development Insights methodology and current tool](/tools/development-insights). These articles explain research methods; they do not reproduce proprietary transaction databases or establish an approval, valuation or future result.

## References

1. [Consumer Affairs Victoria: understanding property prices and underquoting for buyers](https://www.consumer.vic.gov.au/housing/buying-and-selling-property/understanding-property-prices-and-underquoting-for-buyers)

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Source: https://premiumrea.com.au/blog/comparable-sales-small-sample-median
Publisher: PremiumRea (Optima Real Estate) — Melbourne buyers agent