Analogical change is the change of a linguistic item on the basis of an analogy with a similar item. A straighforward example is the change, occurred in the history of Modern English, which transfers a verb from strong into weak conjugation. The following table contains some examples:

Passage into weak conjugation
  phase
originalsubstitute
tense ╲modeltarget
pres.worklurkwork
pastwroughtlurkedworked
pres.knitfitknit
pastknitfittedknitted
pres.shearrearshear
pastshorerearedsheared
pres.swellsmellswell
part.swollensmelledswelled

The verbs in the first column are originally strong verbs, which means they form their past tense by morphological modifications of the root which follow, at best, minor subregularities like one or another apophony class. In present-day English, these verbs make their past tense by suffixing the past-tense suffix -ed to the root, producing the forms marked yellow in the table.

In the relevant historical phase, the language system presents straightforward models for such a change: There are, side by side with the strong verbs, weak verbs which rhyme with these strong verbs but form their past tense by the said suffix. These are listed in the second column of the table.

Analogical change presupposes a model representing the target of the change. It is sometimes assumed that the model must be a schema. In the present case, this would be the schema of weak conjugation, well entrenched in the system. In such cases, analogical change increases regularity in the system. However, this is not always so. During essentially the same period, some English weak verbs moved into the strong class as shown by the next table.

Passage into strong conjugation
  phase
originalsubstitute
tense ╲modeltarget
pres.wearbearwear
pastwearedborewore
pres.tearbeartear
pasttearedboretore

The verbs in the leftmost column were originally regular weak verbs. They developed apophonic past conjugation as shown in the yellow cells on analogy with the irregular verbs of the second column. If there was a schema in these cases, it was not very strong. It is more probable that such particular verbs as listed in the second column served as direct models for the change.

For a proper understanding of analogical change, it is important that the original construction plays no role in the process. Analogical change does not actually operate on the original construcion and modify it. A speaker who creates a construction – in the case of the examples, a verb form – by analogy with an existent verb form or a schema of verb forms makes no use of the traditional construction that would be available for the given purpose. It may be that he has a memory problem because the traditional form is so rare that he cannot presently recall its formation. It may also be that he prefers, for whatever reason, to apply a different model to the task at hand. Thus, analogical change is both creative and conservative. It is creative because it neglects an existent construction and forms a new one in its stead. It is conservative because the construction formed by analogy follows a pre-existent model; it does not introduce a new schema in the language.

It is also important to note that there are analogical changes in converse directions. Analogical change is therefore not intrinsically directed in the sense that there was a principle determining what would serve as a model for a change.

Analogical change also happens at the level of syntax. From Old English to Middle English, the word order in periphrastic constructions changed as illustrated by .

.hiehæfdunheoracyningāworpenne
OEtheyhave:PST:3.PLtheirking(ACC)off.throw:PTCP.PRF:ACC.SG
they had deposed their king(Anglo-Saxon Chronicle A1 I 867.1)

Originally, the direct object in this construction depends on the verb habban ‘have’ and therefore follows it immediately. At the next step, the combination of habban with the participle is reanalyzed as a (periphrastic) verb form. Now the direct object depends on this verb form. In analogy with synthetic verb forms, which had always been followed by their object, the object in this periphrastic construction is then shifted to its new position after the periphrastic verb form.

It may be noted that the change shown by this example involves the interaction of three different mechanisms of change, viz. analogical change, reanalysis and grammaticalization. There are, from this point of view, two varieties of grammaticalization: grammaticalization oriented towards a target on analogy with a model resembling the target, and pure grammaticalization, i.e. grammaticalization without a model in the same language system.