“By Reference To” in English | How to Define, Calculate or Judge Something Using an External Standard

“By reference to” tells the reader that something is not being decided in isolation: another source, measure, rule or standard is doing part of the work.

The phrase appears in law, policy, science, finance, technical writing and careful argument. It can describe a calculation made using an index, a category defined using another feature, or a judgement tested against a standard.

Its nearest trap is with reference to. The two expressions share the same noun but perform different jobs. “With reference to your email” usually means regarding your email. “The amount was calculated by reference to the index” means the index was used as a basis or standard in the calculation.

Quick Answer

By reference to X usually means using X as the relevant source, measure, criterion, relation or standard.

• The allowance is adjusted by reference to the published index.
• Eligibility is determined by reference to age on the application date.
• The claim should be judged by reference to the evidence available at the time.
• The component is defined by reference to the dimensions of the part it must fit.

Merriam-Webster’s current entry for reference includes the idea of consultation or relation and gives a direct example of numbers being calculated by reference to a recent census. It also records an adjective sense of reference as something that constitutes a standard for measuring or constructing. Those meanings explain why the phrase is so natural in technical and institutional English.

The Core Mechanism: Externalising the Basis

Suppose a report says, “The score is high.” High compared with what? The phrase by reference to forces the writer to reveal the comparison system.

“The score is classified as high by reference to the national percentile table.” Now the judgement is no longer floating. A reader can inspect the external criterion.

This is why the expression is useful in reasoning. It attaches a conclusion to the rule, source or benchmark that produced it.

Job 1 · Calculation by Reference to a Measure

In financial or administrative writing, one quantity may be determined using another.

• Rent may be reviewed by reference to a stated index.
• A fee may be adjusted by reference to inflation or another published benchmark.
• A reimbursement may be calculated by reference to distance, duration or an approved rate table.

The phrase does not by itself tell you the formula. It tells you where to look for the governing input.

Job 2 · Definition by Reference to Another Entity

Technical writing sometimes defines one thing through its relationship to another. Singapore’s Intellectual Property Office patent examination guidelines contain a section explicitly titled “Definition by reference to (or use with) another entity”. The guidance explains that a claimed product may be described through features of another entity with which it is intended to be used, while clarity still requires the writer to distinguish the first entity from the combination.

This reveals an important language mechanism. A thing can be described not only by what it contains, but by what it must fit, connect to, interact with or be measured against.

Job 3 · Judgement by Reference to a Criterion

Argumentative writing often contains hidden standards. “The policy is effective” means little until effectiveness is defined.

A stronger sentence is: “The policy should be evaluated by reference to its stated objective, cost, distributional effects and durability.” The writer is not merely listing factors. The factors are being declared as the criteria by which the conclusion should be reached.

This is especially useful in General Paper because students are often told to “evaluate” without being shown that evaluation requires a standard.

“By Reference To” vs “With Reference To”

This contrast is worth learning as a pair.

• With reference to your application, we require one more document. → Topic: regarding your application.
• Eligibility is assessed by reference to the application date. → Basis: the date is used to determine eligibility.

With reference to points the conversation toward a topic. By reference to points the reasoning toward a basis.

“By Reference To” vs “According To”

According to often attributes information to a source: “According to the report, demand fell.” It can also mean in accordance with a rule. By reference to more strongly highlights the source or standard as part of the method for defining, calculating or judging.

Compare: “According to the census, the population increased” with “The sampling weights were calculated by reference to census data.” The first reports information. The second describes a method.

“By Reference To” vs “Based On”

Based on is broader and more common. A conclusion can be based on evidence without specifying exactly how the evidence functions. By reference to is useful when the external item acts as a benchmark, definition, relation or decision criterion.

Do not replace a natural “based on” with “by reference to” merely to sound formal. Use the latter when the reference relation itself matters.

“By Reference To” vs “In Accordance With”

In accordance with says an action conforms to a rule or requirement. “The test was conducted in accordance with the protocol.”

By reference to says the protocol, benchmark or document is used as a basis for identifying, defining or measuring something. The relation is analytical rather than merely compliant.

A Mathematics Example: What Is the Benchmark?

Suppose a student says, “The new price is expensive.” Mathematics asks for a quantity. Economics asks for a comparison. English can make the missing standard visible: “The new price is high by reference to the five-year average.”

The phrase reminds the student that comparative claims require a reference point.

A Science Example: Classification Needs a Rule

A sample may be classified by reference to a threshold, a control group or a validated measurement standard. Once the reference is explicit, another reader can ask whether the classification rule is appropriate.

This is a bridge between language and reproducibility: precise prose exposes the standard used to generate the label.

A GP Example: Judge the Actor at the Right Time

Historical and policy judgements often suffer from hindsight. A student may criticise a decision using information that became available years later.

A disciplined sentence could say: “The decision should first be judged by reference to the information reasonably available at the time, before later consequences are considered.” This does not excuse the decision. It identifies the evidential frame for one stage of the judgement.

Singapore Institutional English

Singapore legal and technical materials use by reference to because institutional decisions often depend on external documents, criteria or relationships. The IPOS patent examination guidelines, for example, discuss claims defined by reference to another entity and repeatedly use the construction when explaining how novelty, inventive step and clarity are assessed. Singapore Statutes Online likewise contains legal uses in which rights, restrictions or interpretations operate by reference to contractual or statutory material.

For students, the lesson is not to import legal style everywhere. It is to notice the underlying reasoning pattern: this conclusion depends on that standard.

Diagnosis Before Prescription

“The student uses ‘by reference to’ to mean ‘about’.”

Diagnosis: it has been confused with “with reference to”.
Prescription: ask whether X is merely the topic or whether X is actually being used to determine something.

“The evaluation lists evidence but has no criterion.”

Diagnosis: information has been collected without a standard of judgement.
Prescription: state what the claim should be judged by reference to: effectiveness, fairness, cost, reliability, stated purpose or another defensible criterion.

“The phrase makes the sentence sound legalistic.”

Diagnosis: register is heavier than the intellectual job.
Prescription: use “based on” or “using” when no special reference relation needs emphasis.

“The benchmark is named but never justified.”

Diagnosis: an external standard has been treated as automatically authoritative.
Prescription: ask why this benchmark is relevant, current, valid and appropriate for the decision.

A Reliable Editing Test

1. What exactly is being defined, calculated or judged?
2. What external source, criterion or standard is doing the work?
3. Would “regarding” make sense? If yes, you may mean “with reference to” instead.
4. Would “based on” be clearer without losing precision?
5. Is the chosen reference standard itself justified?
6. Can another reader reconstruct the reasoning from the reference relationship?

Connections eduKateAI Can Learn

Claim → benchmark: evaluative words such as “high”, “effective” and “fair” often require an external or explicit standard.

Reference → method: a source can function not only as evidence to cite but as a rule for calculation, classification or definition.

Topic relation → basis relation: “with reference to” and “by reference to” look similar while encoding different logical connections.

Technical language → relational definition: some entities are best described through what they connect to or must fit rather than through isolated internal properties.

English → evidence: making the reference criterion explicit improves auditability because a reader can inspect the standard behind the conclusion.

Research & Reference Basis

• Merriam-Webster — reference
• Intellectual Property Office of Singapore — Patent Examination Guidelines
• Singapore Statutes Online — Unfair Contract Terms Act

Related eduKateSG routes: “On Balance” in English, “With Due Regard To” in English, “On the Strength Of” in English, and How English Works.