An Analysis of Errors in Business-Oriented Written Paragraphs of the Thai EFL Undergraduates

Effective written communication is not only a crucial skill for academic achievement but also for business context as it could lead to individual professional career success and profitable accomplishment. To achieve these goals requires concise and correct communication. This study, therefore, aims to explore the most frequently-made errors by 30 Business English major students. From the total number of 14,118 words, the study found that the students most frequently made three types of errors: morphological (17.91%), syntactical (45.37%), and mechanical (36.72%) levels. Of all the errors that occurred, article errors appeared to be the most problematic use (17.31%), followed by punctuation (13.34%), plurality (13.43%), capitalization (9.55%), and preposition (8.96%) errors. The findings suggested that mostly-made errors by the Business English major students were influenced by the interference of their first language. Additionally, apart from explicit grammar teaching, greater exposure to the target language is also required in the classroom. punctuations (13.33%), pluralities (10.45%), capitalizations (9.55%), prepositions (8.96%), spellings (7.76%), spacings (5.97), word classes (5.67), fragments (5.07%), and conjunction (3.58%).

that English as a Foreign Language (EFL) students attempting to write a more creative, content-rich text tend to produce and vary levels of errors in terms of grammar and rhetoric, depending on their proficiency level. He noted that with a plethora of ideas and the attempt to express them, L2 writers with limited knowledge of the target language tend to make errors when they apply the language rules in a comprehensible way. Written medium, compared to spoken, is a constraint when conveying the writer's message for the fact that it disregards the use of voice, intonation, stress, facial expression, and gesture. The writers, therefore, are required to be certain that the message is clear and unambiguous, given that they need to be "educated to construct grammatically acceptable sentences and be able to spell correctly" (Norrish, 1983, p. 65). The correct use of grammatical features through writing, therefore, marks an exceptional communicative competency and professionalism of the writers.

Error Analysis
From Behaviorism to Contrastive Analysis (CA) to Error Analysis (EA), researchers have sought the factors influencing foreign language (FL) learners' incorrect use of the target language. As Corder (1967) pointed out, errors made by language learners are significant in three different ways. First, they unveil what the learners have learned and what they have not. This, for pedagogical purposes, is considered vital for teachers to develop their pedagogical materials. Second, it is the evidence researchers to seek for a better understanding of how the language is learned and what learning strategies are adopted throughout the process of the discovery of the language. Lastly, making errors act as a device the learners use to learn the target language. Understanding learner's error is the key to understanding how learners acquire the target language (Brown, 2000). Most importantly, the error is necessary since it is a part of language learning (Norrish, 1983). Brown (2000) summarized that errors made by language learners can be "observed, analyzed, and classified" (p.218), and in the perspective of error analysis, it is crucial to appropriately identify if the learners' language is a 'mistake' or an 'error'. James (2013) reviewed that to differentiate errors over mistakes, intentionality is the key; without the intention to commit errors, the errors arise. The ungrammaticality made by foreign language learners without knowing it or is not self-correctible is an error. A mistake, however, occurs when they are aware of the incorrectness but do not know how to make it right (James, 2013). Norrish (1983) concluded that errors occur when the language learners, having not learned something, consistently make erroneous utterances or sentences while the inconsistent occurrences of errors -the learners sometimes use a correct form and sometimes do not -are considered mistakes. Another type of wrong usage is a 'lapse'. As Norrish continued, a lapse may be due to lack of concentration, shortness of memory, fatigue, etc. A lapse bears little relation to whether or not a given form in the language has been learned, has not been learned, or is in the process of being learned (p. 8).

Mistakes and Errors
This is not only limited to the FL learners but native speakers can also suffer lapses as the learners of the language do.

Sources of Errors
For EFL as well as ESL learners, the first language takes a significant role in producing the target language. The L1 transfer was argued by James (2013) that it could be considered an error for it reflects the limitation of the L2 competence when the EFL learners attempt to disseminate their message in L2 with L1 equivalence. As discussed in Dulay, Burt, and Krashen (1982) about L2 learners' past knowledge and experience, their native language was applied in the new circumstance, referred to as the target language. L1 interference, in contrast, is unsystematic since it is a performance failure to meet the required target language rules. It is the case when the learners cannot adapt or retrieve the piece of knowledge they need to produce the target language. The interference of L1 is, thus, considered a mistake.
To explore the production of errors made by EFL learners, Brown (2000) suggested two major sources of errors. Interlingual transfer refers to the interference of the learners' first language. This negative interlingual transfer is the result of the differences between the target language and the language the learners previously acquired when they are unsure of the use of the target language and substitute it with their L1 (James, 2013). Such avoidance of the target language, however, is not the only case. The intralingual transfer is "one of the major contributions of … sources of error that extend beyond just interlingual errors in learning a second language" (Brown, 2000, p. 224). Intralingual transfer, also known as overgeneralization, occurs when EFL learners have acquired some knowledge and rules of the target language and incorrectly applied those rules in their language production process. Other popular theories on sources of errors as proposed by Norrish (1983) include carelessness which could be considered as a part of lack of motivation, translation of familiar idiomatic expression of the L1, and incomplete application of rules. elt.ccsenet.org English Language Teaching Vol. 15, No. 7;2022

Classification of Errors
According to James (2013) and Ellis (2005), error analysis can be described in two terms: Linguistic category classification is a specification of the error to locate its occurrence. The level of language error is the first to be identified --phonology, graphology, grammar, lexis, text, or discourse. Should the error be identified as grammar, construction of grammatical features is focused --auxiliary system, passive, sentence complement, word orderand the occurrence of errors is advised to be data-driven (Ellis & Barkhuizen, 2005). After the errors in grammar structures are identified, the data will deal with classes related to the particular performance which involves the class of a noun, verb, adjective, adverb, preposition, determiner, or others. When the class of errors is determined, identifying the rank of the error (morpheme, word, phrase, clause, or sentence) will illustrate the hierarchy of units that form the level. Lastly, the grammatical system --tense, number, voice, countability, transitivity, etc. -will be specified to unveil the effects the errors have on constructing sentences. This study will decode the errors made by Thai Business-English-major students using the notion of linguistic taxonomy method. To exemplify, consider the following error: Darren likes eat apples.
The attempt to use "eating" is a "grammar" level of error, with a word class of "noun" and a system of "finiteness".
Surface structure taxonomy concerns Dulay, Burt, and Krashen's (1982) proposal and James's (2013)  e. blend, learners' undecided choices of the target language (i.e. the mixed use of the alternate words of "past" and "history" in There was no evidence of the existence of Big Foot in the past history.) Those descriptions of errors can be further classified and referenced by three criteria. Modality concerns whether the language learner's behavior is receptive or productive. Medium focuses on identifying if the errors occur when the learner is producing speech sounds or making written symbols. Levels are also identified when the learners make a mistake whether it is a substance (spelling or pronouncing errors), text (lexicogrammatical errors), and discourse (content or conceptual-related errors) level of errors (James, 2013).

Errors in Writing
Teaching grammar is a crucial pedagogical activity of FL learning across the globe. According to Wang (2010), the necessity of learning and teaching grammar to FL learners is to help promote English communicative competence and proficiency. However, with the abundance of grammar points provided in English language teaching books and a limited class time, teachers are in the need to make a decision, on which grammar point to teach and which not to (Folse, 2016). Several research, therefore, aims to discover the most common grammatical error that occurred in students' writing to determine which grammar points needed to be remedied and emphasized for the development of teaching materials and the re-design of the pedagogical plan and activities. Among those, the several studies on errors made by undergraduate and graduate students in writing mainly focused on identifying erroneous texts in English for General Purposes (EGP) composition (Sawalmeh, 2013;Phuket & Othman, 2015;Phoocharoensil et al., 2016;Promsupa et al., 2017;Katter, 2019;Suraprajit, 2021) and English for Academic Purposes (EAP) writing (Jie & Cross, 2014;Amiri & Puteh, 2017;Kampookaew, 2020).
Many of the previous studies on error analysis in English essay writing were conducted in the context of the general English essay writing courses for English major and non-English major students and some in English for Academic Purposes (EAP) courses aiming to prepare the students for their term papers. Very few focus on seeking EFL learners' errors in English for Specific Purposes (ESP). Despite the number, most of them focus on studying the written texts of the Business-related major students enrolling in business English courses (Zafar, 2016;Yang, 2020;Uba & Souidi, 2020).

Participants and Context of the Study
The participants were 30 third-year business English students of the Faculty of Humanities and Social Sciences at a university in Northeastern, Thailand. They were native Thai speakers who had spent over 14 years learning English. Their command of the English language was not entirely different. They were at the intermediate level or B1-B2 when compared to the CEFR level. The participants enrolled in the 'English Structure' and the 'English Structural Analysis' courses. They also registered for three compulsory writing courses in their first, second, and third years. The first writing course mainly focused on elements of writing, but the second writing course put more emphasis on business context. The third writing course was business correspondence writing which students were required to write formal business documents. Every participant was in the same class, and they volunteered to participate in the current study.

Data Collection
The data were collected from the participants' paragraph writing. Each of them was required to write two persuasive paragraphs to explain the features, advantages, as well as benefits the customer would get from purchasing a product from them. At the beginning of the study, the participants were informed about the purpose of the study, and all of them had given consent to allow the researcher to analyze their data. The total number of data was 14,118 words. The participants were assigned to write this paragraph as a take-home assignment. They had one week to complete the assignment, and they were allowed to consult only English-English or English-Thai dictionaries. After they finished writing, they emailed the assignment to the researcher.

Collection of Participants' Writing Samples
The data were collected from two persuasive paragraphs written by the participants as take-home assignments.

Identification of Errors
The data set will be analyzed based on the grammatical failures of the participants' performance if they are self-correctable. In this stage, the error types were not set before, but the researcher was driven by the data. The participants' compositions were checked by two coders. Both are Thai EFL teachers who have been teaching English at the tertiary level for over 15 years. The coders separately rated the assignments by reading through each paragraph line by line. They wrote notes when they spotted some errors. For example, the coders wrote 'plural missing' above the word that required plural suffixes, or 'comma misuse' for additions of punctuation 'comma'. The researcher allowed the coder to consult dictionaries.

Classification or Description of Errors
The errors identified were categorized into different types as of 20. As suggested by Kampookaew (2020) that it was very difficult to group all the errors made by students, the most serious ones should be addressed.

Explanation of Errors
The account of a particular error was considered if it was an interlingual error (the interference of the L1) or the intralingual error (the overgeneralization or the ignorance of the restrictive rules of the target language) as suggested by Corder (1975).

Evaluation of Errors
In this final step, the researcher evaluated students' knowledge of the target language as well as the effectiveness of teaching materials and determined the required remedial work.

Results and Discussion
The results of the analysis of Thai EFL students' ESP writing revealed three main error categories: morphological errors (deviant forms in a word level of English written texts), syntactic errors (deviant forms in a sentence level of English written texts), and mechanical errors (deviant forms of rules of English written texts). Morphological errors included errors on singular-plural nouns, word class, and agreements. Syntactic errors involved fragments, run-ons, articles, prepositions, conjunctions, relative pronouns, voices, tenses, and word orders. This also includes the omissions and additions of words that affect the text meaning. Mechanical errors comprised errors in punctuation, capitalization, spelling, and spacing.  Vol. 15, No. 7;2022 Following the 670 errors derived from EFL students' writing, almost half of the students' writing errors were on syntactic level (45.37%), followed by mechanical level (36.72%), and morphological level (17.91%). A total number of 16 types of errors were found in the student writing products. Of all the error types, three errors were associated with three in morphological, 13 were in syntactical, and four related to mechanical levels. Errors on articles ranked first accounting for 17.31%, or just over one-third of all the errors identified at the syntactical level, followed by errors in punctuation with 13.43%, and errors on singulars/ plurals came third with 10.45%. The research also showed that all four errors on the mechanical level ranked top of all the errors that occurred compared to other types of errors.

Errors on Morphological Level
The misuse of singular/ plural forms in Thai EFL students mostly occurred in the case where students misuse the plural nouns by omitting the plural suffixes (-s, -es) although quantifiers were observably presented.
(1) *There are two mode <modes> of light controller which are automatic mode and custom mode.
(2) *Today, we have a promotion for purchasing this product to all customer <customers> which is 10% off.
(3) *The background works won't interrupt you while you're playing game <games>.
(4) * The Xiaomi Mi Watch Lite is one of the cheapest smart watch <smartwatches> you can find.
This finding is consistent with previous research revealing that the problem of omitting the plural suffixes was due to the interference of the first language (Kampookaew, 2020;Promsupa et al., 2017). Unlike English, the Thai language does not distinguish between singular and plural forms even though quantifiers are also present. The use of countable nouns in Thai will always be the same word without any change or addition. With the interference of the Thai L1, several participants use the noun without changing its form or adding any suffix.
The cases of word-class errors included the replacement of present simple with -ing (5), the use of noun instead of a verb (6), the substitutions of noun with an adjective (7), or the replacement of past simple with present simple (8). (5) *Because they Spending <spend> too much time in front of the computer every day without break, so the common symptoms of office syndromes are neck ache, backache.
(6) *MacBook is not the only product that Apple sale <sells>.
(7) *Such shirts are common in the market and sometimes some brands' expensive shirts are the same, but GQ shirts have innovative <innovation>.
(8) Moreover we got a lot of feedback from the customers who bought this watch and most of them satisfy <satisfied> with product.
In English, some word classes, or parts of speech are formed by adding suffixes such as -ing, -ed, -er, -en, or -ion to change their forms and functions. Similarly to English, the Thai language contains complex words -a combination of free and bound morphemes -but there is a great difference in preference that, for the Thai language, the derivation of complex words is rare due to a short list of affixes; most of them do not change the parts of speech but rather add more meaning to the free roots while, in English, adding more than one affixes such as the word 'internationalization (inter -nation -al -ize -ation)' is very productive (Kallayanamit, 2019). With the complex and sophisticated system of English morphological process, it is challenging for Thai EFL students to apply the rules and then causes the incorrect use of words because of these intralingual errors.
Despite the low frequency of errors in subject-verb agreement found in the present study which accounted for only 1.79%, the occurrence was worth mentioning. As presented in (9), the 'there' structure might be the case that caused errors owing to the inverse agreement where the verb forms agree with the nouns after it. For (9), the students might mistake the head noun 'buttons' for 'keyboard'. Another problem causing errors in the subject-verb agreement is the complex use of causative clauses as illustrated in (10). The head noun 'people' which was modified by the relative clause 'who use iPhone' is also the subject of the verb 'has'. However, because the main verb 'made' requires infinitives without 'to', the correct verb form as in (10) should be 'have'.
(9) *There are <is> the perfect bottons keyboard which is the designing called Per-Key.
(10) * iPone13 can work with iPad, Mac devices, and Apple Watch and make people who use iPhone has <have> a good image.
Errors on subject-verb agreements are one of the most frequently made errors among Thai EFL learners who were both English as shown in Promsupa et al. (2017) and Kampookaew (2020) and non-English majors as found in Phoocharoensil et al. (2016) and Suraprajit (2021). It is discussed that such errors were rooted in interlingual errors in which agreement on the subject and its verb forms does not exist in Thai. However, it is crucial to note that the difficulty and complexity of the English structures might be influential factors for EFL students to overgeneralize or ignore the restrictive rules of the English language, which is considered the result of intralingual interference.

Errors on Syntactical Level
The most common errors frequently made by EFL learners as demonstrated in the present study are article errors whether they be the cases of omission (11), addition (12), or misuse (13) of these determiners.
In (11), the phrases of quantifiers such as 'some of', 'none of', or 'all of' require definite article 'the' before the noun, and, as for (12), the English uncountable nouns such as 'sleep', as well as plural nouns, do not necessarily need 'the'. The confusing use of 'the' rules was shown in (13) where the term 'face sunscreen' appeared in the concluding sentences. This was assumed that the noun 'face sunscreen' was previously mentioned and must be preceded by the article 'the' to demonstrate.
(11) *It can dry all of <the> clothes in a short time because it can give hot-air out 360 degrees surround.
(12) *It can analyse your sleep quality by recording complete sleep data such as a deep sleep (13) *As a result, you should purchase a <the> face sunscreen to protect yourself from the harmful effects of UV rays in your daily life.
Following Phoocharoensil et al. (2016) and Kampookaew (2020), preposition errors frequently occur in EFL students' writing. Three subtypes of preposition errors found in the present study included incorrect use of prepositions (14-15), the addition of preposition (16), and omission of the preposition (17).
(14) *If you hesitate to spend your money on this ultra-cheap device or not, you can read some review from <on> the internet, other online shopping as well.
(15) *By <With> these features, this Predator Helios 300 is going to give you the better experience of gaming for sure.
(16) *There is a high technology sensor that tracks for high and low heart rates and also heart rhythms which could be signs of an important condition.
(17) *To sum up, our product is suitable for you to purchase. It can provide you <with> all the best.
Thai EFL students mostly use inappropriate prepositions and unnecessarily add them in their writing. As demonstrated in (14), the student chose 'read from the Internet' over 'read on the Internet', which was the translation of L1. The term '/càk /' in Thai, which means 'from' in English, is usually used when Thai refers to other sources. This was also agreed with the substitution of 'With' for 'By' in (15) where the English word 'by' means '/du:ɪ /' or '/do:ɪ / in Thai when referring to a tool or equipment used to do something. This was considered the result of L1 interference that caused L1 translation.
The misuse of prepositions occurred several times in the present study. In (16), the student added the preposition 'for' despite the transitive verb 'track' does not require a preposition. The ignorance of verb transitivity of Thai EFL students might result from the intralingual error (Phoocharoensil et al., 2016). Furthermore, as shown in (17), the preposition 'with' is omitted. The student was probably familiar with the ditransitive structure which requires two receivers -a direct object and an indirect object -and tried to apply the notion of such structure without adding any preposition, which, repeated (16), was considered to interfere with intralingual errors.
The use of prepositions was also observed by Boonraksa & Naisena (2022) in the aspect of lexical collocation errors. They pointed out that the notion of collocation was not explicitly taught in Thai EFL grammatical classrooms. Errors in grammatical collocation (the use of prepositions after nouns, adjectives, or verbs) were, therefore, due to poor knowledge and limited understanding of the importance of collocations and the interference of L1.
Fragment errors were the most frequently found errors concerning sentence level, accounting for 5.07% (compared to run-on errors with only 1.79%), and the analysis of both sentential errors was discussed in the present study. It was demonstrated that the occurrence of fragment errors ensued as a result of the attempt to write complex sentences with clause modifiers as presented in (18) and (19). According to this, the students might mistake the verb of the relative clause as the main verb of the sentence, or they simply forgot to add the main verb after adding a long, complex modifier. In (20) and (21), the student might refer to the list of examples as a sentence heading, causing him/her to use a noun phrase instead of a sentence.
(18) *Predator Helios 300 <is> the latest version of Acer gaming laptop that will give you an unforgettable experience.
(19) *The fact that you can answer the phone immediately without having to find out where you left your phone and it may cause you to miss a call that will make your life a lot easier.
(20) *Second, sleep monitoring. It can analyse your sleep quality by recording complete sleep data such as a deep sleep, light sleep also give you a sleep score to indicate how well you slept.
(21) *Finally, cheap and quality. It has an affordable price and acceptable quality.
In line with Promsupa et al. (2017), Sermsook et al. (2017), and Kampookaew (2020), problems in structuring incorrect sentences are derived from intralingual interferences. The confusing structures, the incomplete knowledge, or the ignorance of rules of the target language caused learners to inaccurately applied English grammatical rules. The errors in fragments and run-ons, as discussed in Kampookaew (2020), are serious issues that it might affect 'the comprehensibility and interrupt the writing flow' (p. 267). Referring to Myles (2002), the longer and the richer content the students try to construct, the more errors they produce, especially those with low proficiency levels.
As for conjunction errors, several cases of conjunction misuse occurred when the students omit the use of 'and' when listing their examples as presented in (22) and (23). Furthermore, the addition of conjunction as illustrated in (23) was made. The subordinate conjunction of reason 'because' was used as a single word. In Thai, however, it is mostly used in pair (/phrɔ.jɯŋ/ or /phrɔ.dɑŋnɑn/). The addition of 'so' is, therefore, argued that such error was the result of L1 interference. Referring to the error made in (24), despite the similar meaning, the use of 'so' in the middle of the sentence was possibly the overgeneralization of adding the conjunctive adverb 'therefore' within the verb.
(22) *The texture of the gel is clear, not too viscous, <and> not too runny, and rubbing it will quickly absorb into the skin.
(23) *Because they Spending too much time in front of the computer every day without break, so the common symptoms of office syndromes are neck ache, <and> backache.
Agreeing with Phuket and Othman (2015), most of the problems using conjunctions were rooted in the students' incomplete application of rules. On the other hand, the result in the present study supported Suraprajit's findings (2021) as he pointed out that the addition of conjunction was an influence of L1 interference.

Errors on Mechanical Level
Errors on a mechanical level such as punctuations, capitalizations, and spellings were reported in several research (Phuket & Othman, 2015;Phoocharoensil, 2016;Sermsook et al., 2017;Amiri & Puteh, 2017;Khatter, 2019;Kamphhpaew, 2020). The problems using commas and periods -misuse, omissions, and additions -were accounted for 13.43% and considered the second most-made errors in the present study.
(25) *The Genius bed can control the temperature in your room at all times. <,> and can change the temperature according to your body.
(26) *ANA is extracted from many types of Thai flowers: Jasmine, Lotus <,> and Plum Blossom.
(27) *We also use a special material and Air technology (AT), which is breathable and non-restrictive, and has other features such as easy to iron, wrinkle-resistant and non-staining.
(28) *Also <,> including a function that blocks up to 90% of UV rays <,> you can go to work outside without fear of the heat.
It was obvious that students sometimes erroneously substituted commas for periods as presented in (25). The coordinate conjunction 'ands' were intentionally used to join two verbal phrases which shared the same subject. In (26), the omission of a comma also occurred despite the necessity of such punctuation to separate the elements while the addition of a comma preceding 'and' as illustrated in (27) was mistakenly inserted despite the structural usage of the verbal phrase. Moreover, a comma was also omitted in (28) although the introductory word and phrase were present and required a comma to avoid confusion.
Capitalization errors were mostly found due to the students' misconception of proper nouns. As shown in (29), the student referred to the 'Face Sunscreen' as the brand name of the product but wrongly repeated the word with the lower cases since the term 'face' and 'sunscreen' alone are considered common nouns. In contrast, the case in which the student referred to the common nouns as proper nouns was indicated in (30). The students also unnecessarily add upper case (31) and omit capitalization where they are appropriated (32).
(29) *There are three reasons why you should purchase the Face Sunscreen. First, the face sunscreen <Face Sunscreen> feature is very useful for your skin.
(30) *Many people love to use MacBook in terms of General <general> working until Advance <advance> working.
(31) *In this current pandemic situation, It <it> is likely that our new Zoom-centric lifestyle is not going away anytime soon.
(32) *In conclusion, many things and events in the present have an impact on the future. starting <Starting> to learn new things is important to keep in mind, including in the matter of the business itself.
Following Phuket and Othman (2015), Sermsook et al. (2017), and Kampookaew (2020), while the difficulty and complexity of using punctuation arose among Thai EFL learners since such marks are not required when writing in Thai, the rules of capitalizing the first word in the sentence, as well as capitalize proper nouns, are not considered as complex. Additionally, considering the students' level of English language proficiency, capitalization errors were possibly due to their ignorance of English grammatical rules.
Misspellings in another kind of error the EFL student faced when writing in English. What the present study found most problematic in the students spelling errors derived from students' effort to use compound words. Spaces were sometimes omitted or added as presented in (33) and (34); hyphen was, as well, omitted as in (35).
(33) *When the food is cooked, the airfryer <air fryer>will immediately alert you.
(34) *They concern and pay attention to it because there is robbery of information in the Cyber world <Cyberworld>.
(35) *Second, there are many advantages of the iPhone such as it is water resistant <water-resistant>with a rating of IP68, iPhone has Face ID as a system to unlock the device to make it more convenient and safe.
Agreeing with the previous studies, the sources of such errors might be the result of learners' carelessness, confusion of spelling, or inadequate knowledge of compound nouns.
A considerable number of Thai EFL students in the present study committed errors when they doubled the spaces between words as accounting for 5.97%.
(36) *Consequently, you can ^leave the machine to do the cooking, then you are able to enjoy the other activities.
(37) *The function of this machine is to convert ^electrical energy into hot air temperature to cook food, then the food will be cooked and ^people can eat anything without guilt.
Although spacing errors have rarely been reported in other studies on error analysis, the high frequency made, as of 40 tokens, was significant. Referring to James' (2013) notion of lapsology, the problems which were self-corrigibility whether they be "[s]lips, or alternatively lapses, of the tongue or pen, or even fingers on a keyboard" (p. 83) derived from learners' habit and was beyond consciousness. Such relaxed behavior requires a restoration of consciousness to auto-correct the errors.
According to Kampookaew (2020), despite the diversity of EFL learners' language proficiency backgrounds, the use of articles 'the' and prepositions appeared to be one of the most problematic uses of the EFL students. She continued that although the use of these functional words does not affect students' conveyance of meaning, it can lessen the quality and reliability of their writing. In contrast to errors in articles and prepositions, deviant punctuations and pluralities were crucial for they affected the meaning being conveyed. Punctuations significantly contribute to reducing ambiguity, enhancing clarity, and supporting the coherence of the texts (Bruthiaux, 1993;Kulig et al., 2018;Sun & Wang, 2018). As exemplified by Iyer (2021) Preposition errors, however, required detailed analysis. A number of the previous studies (Phoocharoensil et al., 2017;Promsupa et al., 2017;Kampookaew, 2020) viewed the misuse of a preposition as a result of L1 influence while several studies (Phuket & Othman, 2015;Khatter, 2019;Suraprajit, 2021) argued that errors on prepositions occurred because of the ignorance of English restrictive rules. According to the analysis of the present study as presented in Table 2, it was observed that such errors could ensue from both interlingual interference when EFL learners "applied linguistic rules of the native language" (Phuket & Othman, 2015, p. 102) or literally translated their L1 into the target language (Khatter, 2019), and intralingual errors when disregarded (Phoocharoensil et al., 2017) or overgeneralized (Kampookaew, 2020) the use of preposition and caused errors. 10 12 19 n/a n/a

Sources of Errors
Interlingual errors      n/a n/a Intralingual errors        n/a n/a Slips  n/a n/a In line with the previous studies of Promsupa et al. (2017) and Kampookaew (2020), errors found at the morphological (word) level were the greatest; however, it was noteworthy that, in the present study, the high frequency and ranks of mechanical errors were significant. It was observably due to the students' knowledge of English grammatical rules. The students participating in this study had completed the pre-requisite grammar courses of 'English Structure' and 'English Structural Analysis' which equipped them with adequate understanding and usage of the target language, resulting in rare error occurrence of the general English grammar such as agreements of subject and verb. Since most of the problems occurred in the present study were the result of the interlanguage errors (articles, punctuations, pluralities, and prepositions), EFL learners required greater exposure and knowledge of the target language to be aware of the differences between the target language and their mother tongue, of which led to the avoidance of the interference of their L1.
A significant finding of different types of the most common-made errors by English and non-English major students from previous studies arose during the analysis of the present study. Errors in articles, punctuations, pluralities, and prepositions appeared to be the top most problematic grammatical features of EFL learners who, presumably, have intermediate to upper-intermediate levels of English proficiency (Phuket & Othman, 2015;Promsupa et al., 2017;Sermsook et al., 2017;Khatter, 2019). Non-English major students with lower-intermediate levels, in contrast, mostly committed errors in articles, pluralities, agreement of subjects and verbs, and verb tenses and verb forms (Phoocharoensil et al., 2016;Kampookaew, 2020;Suraprajit, 2021).
According to data found, it was argued that the EFL learners who were aware and familiar with the English grammatical rules tended to construct erroneous sentences due to the interlingual interference and rarely make errors derived from intralingual intervention. This might be due to a careful formulation of sentences when writing in English which pertained to their knowledge and understanding of the restrictive rules of English grammar. The low-intermediate EFL learners, on the other hand, were considered to struggle with English composition. Not only did they encounter the complex rules of affixes, verb tenses, verb forms, and subject-verb agreements, but they were also confused with the inexistence of articles as well as countable and uncountable nouns in their mother tongue. To explore the relations between EFL learners' language proficiency, the errors frequently made, and the sources of their errors, a more in-depth analysis of the issue arising from the findings is required.

Conclusion
The present study examined errors made in written texts by 30 Thai EFL students majoring in Business English who are equipped with basic principles of business administration, English communicative skills, and English for specific purposes. Their writing genre was limited to persuasion which might affect the findings and might not apply to other errors made by Thai EFL students from other majors. The study showed that the top ten most common-made errors by participants were errors on the article 'the', accounting for 17.31%, followed by punctuations (13.33%), pluralities (10.45%), capitalizations (9.55%), prepositions (8.96%), spellings (7.76%), spacings (5.97), word classes (5.67), fragments (5.07%), and conjunction (3.58%).
Considering that the students had previously enrolled in the pre-requisite courses of the English grammatical structures in their first and second year, the courses and the teaching materials required a profound shift based on the grammatical errors made by the students. Despite the presence of agreement on subjects and verbs in the courses, a review of pluralities should be considered. The use of articles and punctuations, as well as morphology, requires explicit explanation and pedagogical methods. To master the application of prepositions and spellings, students need massive exposure to the authentic materials of the target language to avoid intralingual interference, and close attention and feedbacks are critical to point out students' fragments and erroneous conjunctions.
To conclude, it is deemed important for students to correctly use the target language. As argued by Kampookaew (2020), grammatical inaccuracy, for academic purposes, could reflect the low quality of writing and affect academic achievement as errors could reflect students' learning process (Phuket & Othman, 2015). For business professional aspects, errors in grammar and spelling cause a huge negative impact on the business. They could result not only in a poor reputation and bad impression (Scaros, 2016;Ranaut, 2018) but also profitable loss of the organizations (Mozafari et al., 2017;Iyer, 2021). Bad grammar, as stated in Hoover (2013), could also lead to employment opportunities. Guffey and Loewy (2013) also noted that failure to clearly disseminate one's thoughts could limit business and professional opportunities. Consequently, students of the Busines English program are required to develop grammatically-correct writing skills for effective, coherent communication, for it is essential for language learners, especially those whose professional goal is to be successful in the business world, to avoid ambiguity and facilitate a better understanding of the messages for a better, clearer, and more precise communication. The study of grammar is, therefore, essential for learners of English to develop and express their thoughts, ideas, and perceptions with confidence in the real business world.