A snapshot of online shopping
Online retail is often associated with easy price comparison, but comparable listings do not necessarily converge on a single price. Japan’s national price survey provides a useful historical example: internet retailers selling Sony’s MZ-E505 in November 2002 reported a range of prices around a fairly narrow central band.
This is a different question from whether prices were rising or whether Japan was expensive compared with other countries. It concerns price dispersion—the variation facing shoppers at the same time for the same named product.
| Measure | Survey period | Reported price |
| Lower quartile | November 2002 | 15,540 |
| Median | November 2002 | 16,500 |
| Average | November 2002 | 16,408 |
| Upper quartile | November 2002 | 17,010 |
The source does not state the unit in the supplied results, so these figures should not be assigned a currency unit without checking the underlying table.
Why the median matters
For Sony’s MZ-E505 in November 2002, the median price was 16,500, while the average was 16,408. Their closeness suggests that the center of the observed online market can be described reasonably well by either measure. Even so, they answer different questions.
The November 2002 average of 16,408 reflects every observed price and can be affected by unusually high or low listings. The November 2002 median of 16,500 identifies the central listing after prices are ordered. For a shopper asking what price was typical, the median may therefore be easier to interpret.
The quartiles show the shopping opportunity
The lower quartile was 15,540 in November 2002, and the upper quartile was 17,010 in November 2002. This means the middle portion of the observed listings occupied a band rather than a single market price.
That band is economically meaningful. A buyer who compared sellers could encounter a lower listed price than someone who stopped at a more expensive shop. Price-comparison tools may reduce search effort, but the November 2002 data show that online availability alone did not erase differences between sellers.
The figures do not explain why the prices differed. The supplied material does not describe shipping charges, stock conditions, seller services, warranties, or other terms. Consequently, the gap should not automatically be interpreted as a difference in the final cost paid by consumers.
A reusable way to read product-price data
This example offers a practical framework for readers in any country. The average indicates the overall center, the median shows the middle listing, and the quartiles reveal how much variation surrounded that center. Looking at all of them is more informative than quoting only one “typical” price.
The November 2002 results concern one Sony product in one sales channel at one point in time. They cannot establish a general pattern for electronics, online commerce, or national inflation. Their value lies elsewhere: they demonstrate how a compact set of distribution statistics can reveal the choices and uncertainty hidden behind a headline price.
出典
- Statistics Bureau of Japan, National Survey of Prices, November 2002: https://www.e-stat.go.jp/dbview?sid=0000100200