Statistics Japanese: 前年比, 季節調整, 標本, 有意差

Core examples: 前年比, 季節調整, 標本, 有意差, 平均, 中央値, 割合, 誤差, 母集団, 推移.

Numbers do not interpret themselves

A news chart says:

前年比3.2％増 季節調整済み 標本数1,200 有意差なし

A learner may understand the numbers but miss the method. Compared with what? Adjusted how? Based on whose answers? Is the change meaningful or noise? Statistics Japanese is full of compact labels that determine whether the number says what people think it says.

The key principle is:

Statistics Japanese must be read by metric, population, comparison, adjustment, and uncertainty.

A number without method is not yet an argument.

前年比

前年比

means compared with the previous year / year-on-year.

Related:

前月比 compared with previous month

前年同月比 compared with the same month of the previous year

前年同期比 compared with the same period of the previous year

This term appears in economics, business, population, tourism, weather, and sales reports.

Learner action: identify the comparison period. A year-on-year increase can coexist with month-on-month decrease.

季節調整

季節調整

means seasonal adjustment.

Related:

季節調整済み seasonally adjusted

季節要因 seasonal factors

原数値 original/unadjusted figure

Some data changes predictably by season: employment, retail, tourism, energy, agriculture. Seasonal adjustment attempts to make period-to-period comparisons more meaningful.

Learner action: check whether the figure is adjusted or raw.

標本 and 母集団

標本

means sample.

母集団

means population, the full group being studied.

Related:

標本数 sample size

抽出 sampling/extraction

無作為抽出 random sampling

回答者 respondents

A survey of 1,000 people is not automatically representative of all Japan. The sample must be understood in relation to the population.

Learner action: ask who was measured or asked, and who the text claims to describe.

有意差

有意差

means statistically significant difference.

Related:

統計的に有意 statistically significant

有意水準 significance level

差が見られる a difference is observed

有意差は認められなかった no significant difference was recognized

A visible difference in a graph may not be statistically significant. Conversely, a statistically significant difference may be small in practical terms.

Learner action: distinguish statistical significance from practical importance.

平均 and 中央値

平均

means average/mean.

中央値

means median.

These are not interchangeable.

If income data has a few extremely high values, the average can be pulled upward. The median tells the middle value.

Related:

最大値 maximum value

最小値 minimum value

分布 distribution

Learner action: ask whether the statistic describes typical value, total value, spread, or rate.

割合 and 率

割合

means proportion/share.

率

means rate.

Examples:

回答者の割合 proportion of respondents

失業率 unemployment rate

増加率 rate of increase

割合 may describe share of a group. 率 often appears as a calculated rate. The distinction is not always hard, but it helps interpret data.

誤差

誤差

means error/margin of error.

Related:

誤差範囲 margin/range of error

推定 estimate

信頼区間 confidence interval

News reports often omit uncertainty. Survey reports may include it. Serious readers should look for it.

推移

推移

means trend/change over time.

Examples:

人口の推移 population trend over time

売上高の推移 sales trend

10年間の推移 change over ten years

推移 is not a single number. It is a time series.

Learner action: read direction, period, and scale.

Graph labels

Statistical Japanese often hides meaning in graph labels:

単位 unit

出典 source

注 note

n= sample size

％ percent

人 people

件 cases

A chart without unit and source should be treated carefully.

Example bank walkthrough

前年比

Year-on-year comparison.

Learner action: identify baseline year.

季節調整

Seasonal adjustment.

Learner action: adjusted or raw?

標本

Sample.

Learner action: who was measured?

有意差

Significant difference.

Learner action: statistical meaning, not just visible difference.

平均

Mean/average.

Learner action: sensitive to outliers.

中央値

Median.

Learner action: middle value.

割合

Proportion/share.

Learner action: part of what whole?

誤差

Error/margin of error.

Learner action: uncertainty.

母集団

Population.

Learner action: group being generalized to.

推移

Trend over time.

Learner action: period and direction.

Stats-sentence check

When reading statistics Japanese:

1. Metric: what is measured?
2. Unit: yen, people, cases, percent?
3. Population: who/what is included?
4. Sample: how many, how selected?
5. Comparison period: previous year, month, same period?
6. Adjustment: seasonally adjusted or raw?
7. Uncertainty: error, confidence, significance?
8. Claim: description, comparison, trend, causation?
9. Source.
10. Graph note or footnote.

Statistics interpretation table

Statistical Japanese should be read by comparison and uncertainty.

Numbers become claims only after method is understood.

Percentage base warning

When reading 割合 or 率, ask:

percent of what?

Examples:

回答者の割合 percentage of respondents

全世帯に占める割合 percentage of all households

前年比3％増 3% increase from previous year

Percent signs look clear. The denominator often is not.

Trend versus cause

推移

shows change over time. It does not automatically prove why the change happened.

If a text moves from 推移 to 原因, look for evidence. If no causal method is described, the claim may only be interpretation.

A strong tool for this article would annotate statistical claims.

Suggested functions:

1. Metric/unit highlighter.
2. Comparison-basis detector.
3. Seasonal-adjustment flag.
4. Sample/population fields.
5. Significance and error labels.
6. Trend visualizer.
7. Causation-warning prompt.

Final rule

Statistics Japanese is not just number Japanese.

前年比 tells comparison. 季節調整 tells method. 標本 and 母集団 tell who is represented. 平均 and 中央値 tell different summaries. 有意差 and 誤差 tell uncertainty. 推移 tells time.

Read the method before trusting the number.