Grammatical Errors in English Essays Written by Thai EFL Undergraduate Students

This study was conducted according to three research objectives: 1) to investigate common types of grammatical errors based on their frequency of occurrence in English essay writing of Thai EFL undergraduate students, 2) to examine the effects of L1 interference on discovered grammatical errors, in particular, to find out whether there were any of the errors influenced by the students’ mother tongue (Thai language), and 3) to provide some essential pedagogical implications for second language learning and teaching. The subjects of this study were 83 second-year students majoring in English at Nakhon Ratchasima Rajabhat University, and they were drawn by using purposive sampling method. The study procedures consisted of 2 steps: 1) the students were asked to write an English essay, and 2) the researcher of this study analyzed the students’ essays by employing the study analysis framework which was adapted from Na-ngam’s (2005) error taxonomy and Richards’ (1971) error categories. The findings indicated that ; 1) there were 26 types of grammatical errors, with the total number of 4,909 errors, occurred in the students’ written work, and the five most common types of all were punctuation, nouns, prepositions, verbs, and articles respectively ; and 2) there were 1,560 out of 4,909 errors, which were categorized into 14 types, caused by the students’ L1 interference, Thai language. The five most frequent numbers of these types of errors fell into the use of plural form of nouns, omission of punctuation, wrong structures of complex sentences, omission of some parts of a sentence, and fragments respectively