Errors are considered to be evidence of the learner's strategy as he or she builds competence in the target language. Various classifications of these error systems have been developed by error analysis theorists, two of which can be helpful for the tutor and are as follows. Interference errors are caused by the influence of the native language, in presumably those areas where the languages differ markedly. Intralingual errors originate with the structure of English itself. The complexity of the language encourages over- generalization, incomplete application of rules, and failure to learn conditions for rule application.
Error analysis can benefit the tutor in several ways.
First, it accounts for many errors which Contrastive Analysis does not. Third, the tutor can use error analysis to classify the error according to a system and correct it by teaching proper target language examples. For instance, if the student consistently forms the past tense by adding -ed to all verbs but can identify and correct them when editing, the tutor may conclude that the student is overextending the rule during the composition of the first draft simply because he or she is concentrating on the ideas expressed rather than on spelling. Instead of reviewing past tense rules, the tutor might elect to stress the need to edit and proofread. Interlanguage Interlanguage can best be understood as an offshoot of error analysis which, as noted above, draws parallels between second language learning and first language acquisition.