Randomize vs Randomise: Which Spelling Is Correct?

Randomize vs Randomise is a spelling difference between American English and several other varieties of English. Both words mean to arrange, select, or assign something by chance. American English generally uses randomize, while British, Australian, and New Zealand English commonly use randomise. However, British writers who follow Oxford spelling may also use randomize.

The difference extends beyond the verb. You will also see randomization vs. randomisation, randomized vs. randomised, and randomizing vs. randomising. These forms appear in statistics, clinical trials, surveys, software documentation, and everyday writing.

Choosing the right spelling depends on your audience, publication style, and technical context. If you are writing for a scientific journal, you should check its style guide. If you are writing for American readers, randomize is usually the appropriate choice. For standard British-style writing, randomise is often the better fit.

What Is the Difference Between Randomize and Randomise?

Randomize and randomise have the same meaning. Both are verbs that describe arranging items, assigning participants, or selecting outcomes through a random process. The difference lies in spelling conventions: American English generally uses the -ize ending, while standard British-style English often uses -ise. Neither spelling is inherently more correct than the other.

For example:

American English: The researcher will randomize the participants.
British English: The researcher will randomise the participants.
Australian English: The application can randomise the order of questions.
Oxford-style British English: The software will randomize the sample.

Each sentence communicates the same idea. The spelling changes to match the writer’s chosen convention, not the action being described.

The verb randomize or randomise commonly appears when someone wants to reduce predictable patterns or assign items without deliberately choosing their order.

Consider a teacher who wants to prevent students from receiving the same quiz questions in the same sequence. The teacher can randomize or randomise the question order. Either spelling works, provided it fits the intended audience and the document’s style.

Randomize: Meaning and Example Sentences

Randomize means to arrange, select, or assign something according to a random process. It is the standard spelling in American English and also appears in Oxford-style writing.

Writers use this form in everyday instructions, statistical explanations, scientific reports, and technical documentation.

Examples of randomize in context:

The teacher will randomize the questions before printing the quizzes.
Researchers randomized the participants into two treatment groups.
The website can randomize the order of product recommendations.
We need to randomize the sample to avoid a predictable selection pattern.
The game uses a system to randomize the order of events.
The analyst randomized the records before conducting the test.

Notice that the spelling remains consistent as the verb changes tense. American writers use randomize, randomized, and randomizing.

In statistical writing, randomization has a specific practical role. For example, a researcher might assign eligible participants to a treatment group or a control group through a random allocation process. This can help reduce selection bias, although the quality of the study also depends on its design, implementation, and analysis.

Randomise: Meaning and Example Sentences

Randomise is an alternative spelling of randomize. It is common in British, Australian, and New Zealand English, particularly in publications that favor -ise endings.

The word has the same meaning and grammatical function as its American counterpart. You can use it to describe a randomized experiment, a shuffled playlist, or a randomly ordered survey.

Examples of randomise in context:

The teacher will randomise the questions before distributing the test.
The research team randomised the participants into separate groups.
The application can randomise the order of the survey items.
Please randomise the entries before running the analysis.
The system randomised the selection process to reduce predictable patterns.
The developer is randomising the order of the cards.

These sentences work naturally in British-style English. Their meanings do not differ from the corresponding sentences that use randomize.

One common mistake is to treat randomise as a spelling error simply because it looks unfamiliar to an American reader. That assumption ignores regional spelling conventions. The correct choice depends on the English variety and style requirements you follow.

Randomize vs Randomise: Regional Spelling Rules

Randomize vs Randomise is mainly a regional spelling question. American English generally prefers randomize, while British English commonly uses randomise outside Oxford-style conventions. Australian and New Zealand writing also commonly favors randomise. Canadian English often uses randomize, though individual publishers and institutions may set their own rules.

These are general conventions rather than absolute laws. English spelling varies across publishers, universities, scientific journals, and professional organizations. When a publication provides a house style, that guidance should take priority over a broad regional preference.

American English: Use Randomize

In American English, randomize is the conventional spelling. The same pattern applies to related words such as randomized, randomizing, and randomization.

American writers generally use the -ize ending in words that allow this spelling pattern. Examples include organize, recognize, and standardize. However, not every word ending in a similar sound follows the same rule, so writers should still check unfamiliar terms.

Examples of American usage include:

The researcher will randomize the treatment assignments.
The application can randomize the list automatically.
The team completed the randomization procedure before collecting the results.
The researchers used a randomized controlled trial to evaluate the intervention.

In business writing, American spelling is also common in product instructions, software manuals, educational resources, and research summaries.

Imagine a US-based company preparing a report about a survey experiment. The report uses analyze, organize, and standardize throughout. Writing randomise in the same report would introduce an unnecessary spelling inconsistency. The writer should normally choose randomize to match the rest of the document.

Practical rule: If your main audience is in the United States, use randomize and its related forms unless a required style guide specifies otherwise.

British English: Randomise or Randomize?

In British English, randomise is common in writing that follows the familiar -ise convention. The same pattern appears in randomised, randomising, and randomisation.

For example:

The team will randomise the participants.
The researchers conducted a randomised experiment.
The software supports automatic randomisation.
The editor asked the writer to standardise the spelling throughout the report.

However, British English does not require every eligible word to use -ise. Some British publishers and writers follow Oxford spelling, which favors -ize in many words.

That means a British publication can legitimately use randomize while retaining other British conventions, such as colour and centre. The spelling system does not have to be entirely American or entirely British in every respect.

For example, an Oxford-style British document might contain the following sentence:

“The researchers randomized the participants before beginning the trial.”

A publication following a standard -ise style might instead write:

“The researchers randomised the participants before beginning the trial.”

Both are acceptable within their respective conventions.

Practical rule: For ordinary British-style writing, use randomise if that matches the document’s spelling system. If your employer, university, or publisher follows Oxford spelling, use randomize instead.

Canadian English: Which Spelling Is Preferred?

Canadian English often uses randomize, particularly in technical and academic contexts.

For example, a Canadian publication may use colour rather than color but still use randomize rather than randomise. This combination is not inconsistent if it follows the publication’s chosen standards.

Consider these examples:

The Canadian research team will randomize the participants.
The analyst completed the randomization procedure.
The software can randomize the sample before analysis.

For professional writing, the best approach is to check the organization’s editorial policy. A Canadian university, government department, or scientific journal may prescribe specific spellings.

If no guidance exists, randomize is a reasonable default for Canadian English, especially in technical writing. Once you choose that form, keep the same spelling in the title, abstract, tables, captions, and main text.

Australian and New Zealand English: Use Randomise

Australian and New Zealand English commonly favor randomise in general writing and in publications that follow traditional British-style spelling.

Examples include:

The teacher will randomise the quiz questions.
The researchers randomised the study participants.
The application uses randomisation to generate a new sequence.
The administrator is randomising the entries.

These spellings align with other familiar forms such as organise, recognise, and standardise.

However, professional and academic writing may follow an institution-specific style guide. An Australian researcher submitting a paper to an international journal should check the journal’s spelling requirements instead of assuming that local spelling preferences will apply.

The same principle applies to New Zealand publications. Regional convention offers a useful starting point, but the target publication determines the final choice when it has explicit requirements.

Practical rule: Use randomise for ordinary Australian and New Zealand writing unless your publisher or organization requests a different convention.

Randomize vs Randomise: Spelling Comparison Table

The table below summarizes common regional preferences for randomize and randomise, along with their related noun forms.

Region or context	Common verb spelling	Common noun spelling	Example
United States	Randomize	Randomization	Randomize the sample before analysis.
Canada	Randomize	Randomization	The team completed the randomization procedure.
United Kingdom, -ise style	Randomise	Randomisation	Randomise the question order.
United Kingdom, Oxford style	Randomize	Randomization	Randomize the participants before the trial.
Australia	Randomise	Randomisation	Randomise the treatment assignments.
New Zealand	Randomise	Randomisation	The application supports randomisation.

The table reflects common preferences, not rules that every writer or publication must follow.

For instance, a British medical journal may use randomized because it follows an international editorial style. Similarly, an Australian software company might use randomize in its documentation to align with a particular codebase or corporate style guide.

When choosing a spelling, consider three questions:

Who will read the content? Regional conventions help you select the expected spelling.
Does a style guide apply? A publisher’s instructions may override general preferences.
Have you used the spelling consistently? Switching between variants can make a document look poorly edited.

These checks take little time and prevent avoidable editing problems.

Randomize or Randomise in Academic and Scientific Writing?

In academic and scientific writing, randomize and randomise describe the same process. The spelling choice depends on the journal’s editorial style, the institution’s requirements, and the conventions used throughout the manuscript. Researchers should preserve scientific accuracy while maintaining consistent spelling in the title, abstract, methods, results, tables, and supplementary materials.

Scientific writing makes this distinction especially important because the words appear in established terms such as randomized controlled trial, random allocation, and randomization procedure.

A spelling variant does not change the scientific method. However, an imprecise description of that method can affect how readers interpret the research.

Randomize vs Randomise in Clinical Trials

A randomized controlled trial (RCT) is a study in which participants are assigned to different groups using a random allocation process. Researchers often compare an intervention group with a control group to evaluate the effects of a treatment or another intervention.

In British-style writing, the same study may be called a randomised controlled trial.

Both phrases refer to the same general study design. The spelling does not determine whether the allocation process was genuinely random or whether the trial followed sound research practices.

Consider a hypothetical trial involving 200 eligible participants. Researchers assign 100 participants to receive a new intervention and 100 to receive a comparison treatment using an appropriate random allocation procedure.

An American report might say:

“The researchers randomized 200 participants into two groups.”

A British-style report might say:

“The researchers randomised 200 participants into two groups.”

Both sentences communicate the same allocation process. The actual study quality depends on the randomization method, allocation concealment where appropriate, participant follow-up, outcome measurement, and statistical analysis.

Researchers should also distinguish random assignment from random sampling. Random assignment determines which study group a participant enters. Random sampling concerns how researchers select people or observations from a population. These concepts serve different purposes, even though both involve chance.

When preparing an RCT manuscript, check the journal’s author guidelines before deciding between randomized controlled trial and randomised controlled trial. Some journals require a particular style, and the abstract should follow the same convention as the rest of the paper.

Randomization vs. Randomisation in Statistics

Randomization and randomisation are noun forms of the verb randomize or randomise. They describe the use of chance in assigning, selecting, or ordering items.

The American spelling is randomization. The common British-style alternative is randomisation.

Randomization appears in several statistical and research settings:

Experimental design: Assigning participants or experimental units to treatment conditions by chance.
Survey administration: Randomizing question order to reduce predictable order effects.
Simulation: Generating random inputs to study how a model behaves under different conditions.
Sampling procedures: Using a suitable random selection method when selecting observations from a population.
Quality control: Randomizing the order in which samples undergo testing to help reduce systematic effects from time or processing order.

Consider a manufacturing company testing whether a new production process improves product strength. If the company always tests the old process in the morning and the new process in the afternoon, differences in temperature or equipment conditions could influence the results.

Randomizing the test order can help prevent the testing schedule from becoming systematically associated with one process. Researchers may still need to control other variables, but randomization reduces one potential source of bias.

The spelling does not change the underlying statistical principle. A report that uses randomisation can describe the same method as a report that uses randomization.

Which Spelling Should Researchers Use?

Researchers should follow the target journal’s author guidelines whenever possible. That decision is more reliable than assuming every journal uses American English or that every British publication prefers -ise.

Before submitting a manuscript, check these areas:

Journal instructions: Look for the required English variety and spelling conventions.
Existing terminology: Check how the journal writes terms such as randomized controlled trial.
Manuscript consistency: Use the same form in the abstract, main text, headings, tables, figures, and supplementary files.
Reference accuracy: Preserve spelling in quoted titles and official publication names rather than silently changing the original wording.
Statistical precision: Describe the actual randomization method accurately instead of relying on the word alone.

For example, a researcher may write randomization in the methods section but randomisation in a table caption after copying material from another document. This is a simple editorial inconsistency that a final spelling review can catch.

A useful workflow is to choose the required spelling before drafting the manuscript. Then use the document editor’s find-and-replace function carefully to locate inconsistent variants. Review each replacement in context, especially when terms appear inside quotations, reference titles, code, or official names.

The goal is not to force every scientific publication into one international spelling system. It is to make the manuscript consistent with the intended publication while preserving the meaning of the research.

The Oxford Spelling Exception: Why Some British Writers Use Randomize

Oxford spelling is a convention that favors -ize endings in many words where that suffix is appropriate. It explains why a British writer may use randomize even when the rest of the document follows British English conventions.

The distinction matters because many readers assume that -ize is exclusively American. That assumption is incorrect. Both -ize and -ise have a long history in English usage, and publishers make different editorial choices about them.

What Is Oxford Spelling?

Oxford spelling is an editorial convention associated with Oxford University Press and other writers or publishers that follow similar practices. It favors -ize in many words derived from forms that support that ending.

Examples include:

Randomize
Organize
Recognize
Standardize
Realize

In this convention, the letter z is not a sign that the writer has switched entirely to American English. A British publication may use randomize alongside forms such as colour, centre, and travelling.

Oxford-style spelling also does not mean that every word ending in a similar sound should take -ize. Some words have established spellings that follow different patterns. Writers should follow the relevant dictionary or house style for uncertain cases.

The important point is that spelling conventions can combine features from different historical and editorial traditions. A British document does not become incorrect simply because it uses randomize.

Is Randomize Correct in British English?

Yes. Randomize is acceptable in British English, especially in publications that follow Oxford spelling or another style that prefers the -ize ending.

At the same time, randomise remains common in British writing. Many readers will expect the -ise form in publications that use standard British-style spelling.

Here are two examples:

Oxford-style British English:

“The software will randomize the order of the survey questions.”

British English using the -ise convention:

“The software will randomise the order of the survey questions.”

Neither sentence is automatically wrong. The correct editorial choice depends on the convention the writer has selected.

If you are writing for a British university, check its style guide rather than assuming it follows Oxford spelling. If you are editing an established publication, preserve its existing conventions unless the editor requests a change.

This approach prevents a common mistake: changing every -ize word to -ise merely because the target audience lives in the UK.

Randomization vs. Randomisation: Related Word Forms

The difference between randomize and randomise carries over to several related words. Writers should use a consistent spelling pattern when forming the past tense, present participle, and noun.

For most ordinary uses, the forms follow a predictable pattern.

Word form	American and Oxford-style spelling	Common British *-ise* spelling
Base verb	Randomize	Randomise
Past tense	Randomized	Randomised
Present participle	Randomizing	Randomising
Noun	Randomization	Randomisation
Adjective	Randomized	Randomised

These pairs have the same basic meaning. The choice depends on the spelling convention used in the document.

Verb Forms: Randomize, Randomized, and Randomizing

American English and Oxford-style writing use randomize, randomized, and randomizing.

The base verb describes the action. The past-tense form describes an action that has already happened, while the present participle often appears in continuous tenses or as a modifier.

Examples:

Base verb: The analyst will randomize the sample.
Past tense: The team randomized the participants yesterday.
Present participle: The software is randomizing the questions.
Adjectival use: The researchers evaluated a randomized design.
Noun use: The randomization occurred before the intervention began.

The spelling remains consistent across these forms. If your document follows American English, use the z spelling throughout unless a quotation or proper name requires a different form.

Verb Forms: Randomise, Randomised, and Randomising

Writers following standard British-style -ise conventions commonly use randomise, randomised, and randomising.

Examples:

Base verb: The analyst will randomise the sample.
Past tense: The team randomised the participants yesterday.
Present participle: The software is randomising the questions.
Adjectival use: The researchers evaluated a randomised design.
Noun use: The randomisation occurred before the intervention began.

These forms communicate the same ideas as their -ize counterparts.

Be careful when editing material from several sources. A British-style report may contain randomised in the methods section and randomized in a copied figure caption. Neither form changes the scientific meaning, but the inconsistency can distract readers and make the document look unfinished.

Noun and Adjective Forms

The spelling difference also appears in nouns and adjectives derived from the verb.

Randomization refers to the process or procedure of making something random. Randomisation has the same meaning in the British-style spelling convention.

Likewise, randomized and randomised can describe a study, experiment, or allocation procedure that has undergone randomization.

Examples include:

The team documented the randomization procedure.
The report describes the randomisation procedure.
The study used a randomized allocation process.
The study used a randomised allocation process.

The main editing rule is simple: choose the relevant spelling convention and apply it to all related forms.

If you use randomize, the matching forms are generally randomized, randomizing, and randomization. If you use randomise, the matching forms are generally randomised, randomising, and randomisation.

Do not assume that changing one letter in the base verb is enough. The noun and participle forms need the corresponding spelling change too.

Randomize vs Randomise in Programming and Technical Documentation

In programming, the difference between randomize and randomise matters less as a regional spelling issue and more as a question of exact syntax. Programming languages and software libraries define specific function and identifier names. You cannot safely change those names just to match the spelling convention used in the surrounding prose.

A technical writer can use randomise in a British-English explanation while preserving an API name that contains randomize, if that is the exact name supplied by the software.

Does Randomize or Randomise Work in Code?

There is no universal rule that every programming language uses a function named randomize. Some languages and libraries provide functions or methods named random, while others provide different interfaces for random-number generation or shuffling.

For example, Python’s standard random module includes functions such as random() and shuffle(). JavaScript provides Math.random() for generating a pseudorandom number between zero and one, excluding one.

These exact names are part of the programming interface. Replacing a function name with a regional spelling variant will not work unless that identifier actually exists in the relevant environment.

Consider this JavaScript expression:

const value = Math.random();

The function name is Math.random(), not Math.randomize() or Math.randomise(). Changing the method name would fail because the standard Math object does not define those alternatives.

Similarly, Python code can use:

import random

random.shuffle(items)

Here, shuffle() is the defined method used to shuffle a list in place. Replacing it with randomise() would not work simply because the programmer prefers British spelling.

This distinction is important: natural-language spelling and programming syntax follow different rules.

How to Choose the Right Spelling in Technical Documentation

When writing software documentation, separate explanatory prose from literal code.

Use these guidelines:

Follow the documentation’s language style. American documentation may use randomize, while British documentation may use randomise in prose.
Preserve exact API names. Do not change function names, method names, variable names, or command-line options to match a regional spelling preference.
Copy code accurately. Code examples should reflect the actual programming language and library.
Explain the intended action clearly. If the documentation says that a function randomizes a list, explain whether it shuffles the list, generates random values, or performs another operation.
Distinguish random generation from shuffling. Generating a random number is not the same operation as rearranging a collection of items.

For example, a British-English manual could say:

“Use the random.shuffle() method to randomise the order of the items in the list.”

The prose follows British spelling, while the code retains its exact API name.

An American-English manual might say:

“Use the random.shuffle() method to randomize the order of the items in the list.”

Both sentences are correct. The technical identifier remains unchanged.

Common Mistakes When Using Randomize and Randomise

Most mistakes involving randomize and randomise arise from confusing regional spelling preferences with grammar, scientific meaning, or technical syntax.

The following table highlights common errors and how to avoid them.

Common mistake	Why it causes a problem	Better approach
Calling randomise universally incorrect	It ignores established British-style spelling	Recognize both variants as correct
Assuming every British writer must use randomise	Some British publications follow Oxford spelling	Check the relevant style guide
Switching between randomization and randomisation	It creates an inconsistent document	Choose one convention and apply it throughout
Renaming a software function to match regional spelling	The identifier may not exist	Preserve the exact API or method name
Treating random sampling and random assignment as identical	They describe different statistical processes	Explain which process the study actually uses
Assuming spelling determines scientific quality	Spelling does not establish whether a method is valid	Describe and evaluate the method itself

A practical example shows why consistency matters.

Imagine an editor reviewing a report written for an Australian audience. The introduction uses randomise, the methods section uses randomized, and a chart caption uses randomization. Each form is recognizable, but the mixed spelling suggests that the author has combined material from different sources without a final style review.

The editor should first check the organization’s preferred convention. If the report follows Australian -ise spelling, the editor can change the prose to randomise, randomised, and randomisation. If the report follows an international journal’s specified style, the editor should apply that style instead.

The editor should not change exact software identifiers, official titles, or direct quotations merely to force uniform spelling.

A quick proofreading checklist can prevent most of these issues:

Identify the intended audience.
Check the publication’s style guide.
Select randomize or randomise.
Check the corresponding noun, adjective, and verb forms.
Review headings, tables, captions, and quotations.
Preserve exact technical names and source titles.

These steps make the article easier to read without changing its meaning.

Frequently Asked Questions

Is “Randomise” a Real Word?

Yes. Randomise is a recognized spelling commonly used in British, Australian, and New Zealand English. It means the same thing as randomize: to arrange, select, or assign something by chance. The -ise ending reflects a regional spelling convention rather than an error.

Is It Randomize or Randomise in the UK?

Both spellings appear in British English. Randomise is common in publications that follow standard British-style -ise spelling, while randomize is used by writers and publishers who follow Oxford spelling. Check the relevant publication’s style guide if you need to choose one form for formal writing.

Should I Write “Randomized Controlled Trial” or “Randomised Controlled Trial”?

Both forms are used. Randomized controlled trial is common in American English and publications using -ize spelling, while randomised controlled trial is common in British-style writing. Researchers should follow the target journal’s instructions and use the same spelling throughout the manuscript.

Is “Randomization” or “Randomisation” Correct?

Both are correct regional variants. Randomization is standard in American English and Oxford-style writing, while randomisation is common in British, Australian, and New Zealand publications that favor -ise endings. Neither spelling changes the statistical meaning of the term.

Does Randomize Mean Something Different From Randomise?

No. The two words have the same meaning. Both describe arranging, selecting, or assigning something through a random process. The difference is spelling, not scientific method, grammar, or intended result.

Which Spelling Should I Use in Programming?

Use the exact function, method, or identifier defined by the programming language or library. Do not replace an existing name with randomize or randomise unless that name is actually supported. In explanatory prose, follow the spelling convention used by the rest of your technical documentation.

Conclusion: Choose Randomize or Randomise Consistently

The difference between Randomize vs Randomise comes down to regional spelling preferences and editorial style. American English generally uses randomize, while British, Australian, and New Zealand English commonly use randomise. Canadian English often favors randomize, and Oxford-style British writing may also use the -ize form.

The related words follow the same pattern. American and Oxford-style writing commonly uses randomization, randomized, and randomizing. Standard British-style writing often uses randomisation, randomised, and randomising.

For academic work, check the target journal’s author guidelines before submitting your manuscript. In programming, preserve exact function names and syntax instead of adapting them to regional spelling.