computer science

Variable rules analysis

Variable rules analysis is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Variable rules analysis rather than just read about it. In short: Variable rules analysis is a set of statistical analysis methods in linguistics that are commonly used in sociolinguistics and historical linguistics to describe patterns of variation between alternative forms in language use. It is also sometimes known as Varbrul analysis, after the name of a software package dedicated to carrying out the relevant statistical computations (Varbrul, from "variable rule").

Key takeaways

Variable rules analysis belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Variable rules analysis to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Variable rules analysis from memory before moving on to harder problems.

Reference excerpt

Variable rules analysis is a set of statistical analysis methods in linguistics that are commonly used in sociolinguistics and historical linguistics to describe patterns of variation between alternative forms in language use. It is also sometimes known as Varbrul analysis, after the name of a software package dedicated to carrying out the relevant statistical computations (Varbrul, from "variable rule"). The method goes back to a theoretical approach developed by the sociolinguist William Labov in the late 1960s and early 1970s, and its mathematical implementation was developed by Henrietta Cedergren and David Sankoff in 1974. A variable rules analysis is designed to provide a quantitative model of a situation where speakers alternate between different forms that have the same meaning and stand in free variation, but in such a way that the probability of choice of either the one or the other form is conditioned by a variety of context factors or social characteristics. Such a situation, where variation is not entirely random but rule-governed, is also known as "structured variation" or "orderly heterogeneity". A variable rules analysis computes a multivariate statistical model, on the basis of observed token counts, such that each determining factor is assigned a numerical factor weight that describes how it influences the probabilities of choice of either form. This is done by means of stepwise logistic regression, using a maximum likelihood algorithm. Although the necessary computations required for a variable rules analysis can be carried out with the help of mainstream general-purpose statistics software packages such as SPSS, it is more often done by means of a specialised software dedicated to the needs of linguists, called Varbrul. It was originally written by David Sankoff and currently exists in freeware implementations for Mac OS and Microsoft Windows, under the title of Goldvarb X. There are also versions implemented in the statistical language R and therefore available on most platforms. These include R-Varb and Rbrul. Variable rules approaches are commonly employed for the analysis of data in sociolinguistic research, especially in studies that aim to investigate how reflexes of linguistic change through time appear in the shape of structured variation patterns within a speech community.

Worked examples

Example 1 — a first encounter with Variable rules analysis

Start with the simplest possible case. Write down what Variable rules analysis claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Variable rules analysis before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Variable rules analysis ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Variable rules analysis

In research: Variable rules analysis appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Variable rules analysis in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Variable rules analysis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computational linguistics stubs, Linguistic research software, Logistic regression, so understanding it makes those chapters shorter.
In everyday life: Look for Variable rules analysis outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Variable rules analysis in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Variable rules analysis means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Variable rules analysis out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Variable rules analysis in simple terms?

Why does Variable rules analysis matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Variable rules analysis?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Variable rules analysis.