22 language” and mistakes are “deviation in usage that reflects learner’s inability to
use what they actually know the target language” Ellis, 1997:141. It means that errors occur because the learner does not really understand the correct forms and
mistakes are made by carelessness that actually the learner understands correct forms. However, in this research, the researcher only discusses errors in order to
find the students’ errors in defining and non-defining relative clauses. In order to discuss errors in depth, here are the definition and classification of error.
a. Definition of errors
According Ellis and Barkhuizen 2005:56, errors are defined based on two views, grammaticality and acceptability. In grammaticality, they cite that an
error is “a breach of the rule of the code”. They state that it depends on the view that “what particular variety of the target language is chosen as the code” Ellis
and Barkhuizen, 2005:56. It means that errors break the rules of a variety of a target language as a code. On the other side, based on the acceptability, Ellis and
Barkhuizen 2005:56 define that an error is “more dependent on the subjective evaluation of the researcher ...” and also “involves attempting to identify a
situational context ...” Ellis and Barkhuizen, 2005:56. It can be said that errors are dependable and based on the context used.
Because of those uncertainties of the distinction of grammaticality and acceptability, those theories were blurred. Then, Ellis and Barkhuizen 2005: 56
cite that errors refer to “a linguistic form or a combination of forms which, in the same context and under similar conditions of production, would, in all
23 likelihood, not be produced by speakers’ native speaker counterparts” Ellis and
Barkhuizen, 2005: 56. It is clearly that errors happen in the same context and condition of production and are unlike what native speaker counterparts produce.
In this research, the researcher searched the students’ linguistic forms that are produce unlikely as the native speaker counterparts produce defining and non-
defining relative clauses.
b. Classifications of errors
Ellis and Barkhuizen 2005:60 classify errors based on the system of category, which is named taxonomy. There are two kinds of taxonomy they
describe, linguistic taxonomy and surface structure taxonomy. 1 Linguistic Taxonomy
Linguistic taxonomy is drawn by descriptive grammar, which is famously called descriptive taxonomy. In English descriptive grammar or
descriptive taxonomy, a grammar includes: a General categories such as sentence structure, verb phrase, noun phrase,
preposition phrase, etc. b More specific categories such as:
1. Verb tenses e.g. simple present tense, simple past tense, etc. 2. Aspect e.g. perfective, progressive, etc.
3. Auxiliary verbs which are divided into primary e.g. is, am, are, etc and modal e.g. can, may, will, etc.
4. Other specific categories.
24 “Errors should be classified in terms of the target language categories that have
been violated rather than the linguistic categories used by learner” Ellis and Barkhuizen, 2005: 60. Therefore, errors are classified based on the violation
happening in the target language categories. Those errors are different from the linguistic categories the learner learns.
2 Surface Structure Taxonomy
Dulay, Burt, and Krasen 1982:150 that surface structure taxonomy is
drawn based on “the ways surface structures are altered” Then, based on surface structure taxonomy; they suggest four principles of the learner’s errors:
a Omission The errors come because of the omission of a form that should appear in
the construction of a sentence. For instance, the omission of auxiliary verb be in the sentence I beautiful. It should be I am beautiful.
b Addition The errors come because of the presence of a form that should not appear
in the construction of a sentence. It happens in these sub-categories:
1. Regulation, for instance she eated soto yesterday it should be she ate soto
