lexical density and readability: a case study of english textbooks

LinguisticcomplexityLexicaldensityReadability

Lexical density is “the kind of complexitythat is typical of written language”(Halliday, 1985, p.62)

LinguisticcomplexityLexicaldensityReadability

Readability "depends on several factors includingthe average length of sentences, the number ofnew words contained, and the grammaticalcomplexity of the language used in a passage.”(Richards, et al.,1992, p.306)

Identify the changes of lexical density and readability; Find out the relationship between lexical density,readability and text levels; Discover the consistency between the measurementsof lexical density and readability.

1. How do lexical density and readability change acrosslevels in the selected texts in English textbooks?2. What is the relationship between lexical density,readability and text levels?3. What is the correlation between the methods adopted toaccess lexical density and readability?

1. Ure’s method:How to measure LEXICAL DENSITY?Lexical density =the number of lexical items x 100the total words(Ure, 1971; Halliday, 1985)When you heat a liquid, it can change into gas.

1. Ure’s method:How to measure LEXICAL DENSITY?Lexical density =the number of lexical items x 100the total words(Ure, 1971; Halliday, 1985)When you heat a liquid, it can change into gas.• Lexical density: 40%

Grammatical items:Determiners, pronouns, most prepositions, conjunctions,some classes of adverb and finite verbs. (Halliday, 1985) Lexical items:Nouns, verbs, adjectives and adverbs are the four word classesbelonging to lexical items (T.Le, Yue, & Le, 2011).

Some kinds of lexical items and grammaticalitems were determined differently by linguistsand researchers in literature(To, V. et al., 2013)

Halliday (1985) /Ure (1971): Phrasal verbs: give up, eat out O’Loughlin (1995): All prepositions, conjunctions, quantifiers Castello (2002, cited in Castello, 2008, p.56-57) :3-word sequence prepositions: in view of, in terms ofopen-class quantifiers: heaps of, a great deal ofcomplex conjunctions and subordinators: provided that,regardless of

“it does not matter exactly where we drawthe line provided we do it consistently”.(Halliday, 1985, p.63)

Halliday (1985) O’Loughlin (1995) Ure (1971) Castello (2002)

(To, V. et al., 2013b)

All NOUNSAll LEXICALVERBSAllADJECTIVESWord Class• university, David, Apple• Eat, read, thinkold, beautiful, usefulNotesA compound noun /phrasal verb /compoundadjective - a lexical itemE.g. long-term, eat out,good-lookingTwo kindsof ADVERBS• Manner adverbs: quickly, beautifully• Sentence adverbs: honestly, fortunately

Word classExamplesAllPRONOUNS• Personal pronounsI, you, she, them, one• Demonstrative pronouns this, that, these, those• Possessive pronouns• Reflexive pronouns• Indefinite pronounsmine, yours, his, hers, its,myself, yourself, himselfnothing, anyone, another

Word classExamplesAllDETERMINERS• Articlesa, an, the• Possessiveadjectives• Quantifiers• Numeralsmy, your, his, hersome, any, many, few,one, sixteen, second, third

Word classExamplesAll FINITE VERBS • Be• Do• Have• Modalsam, is, are, was, were, beendo, does, didhave, has, hadcan, may, probably, certainly

Be, Do, Have as main verbsLexical itemsBe, Do, Have as auxiliariesGrammatical items• I am a student.• I am talking.He was beaten.• I have cereal for breakfast.• The student did his homework.• You have done a good job.• Did the student do hishomework?

Word classExamplesSomeclasses ofADVERBS• Temporal adverbs• Locative adverbsnow, then, today, always, later,beforehand, afterwardshere, there, below, above,outside, upstairs, indoors• Degree adverbs• Negative andInterrogative ADVvery, too, so, rather, quiteNot, never, when, where, how

Word classExamplesAll CONJUNCTIONSAll PREPOSITIONSAll DISCOURSE MARKERSAll INTERJECTIONSAll REACTIVE TOKENSand, but, however, thereforein, at, of, with, betweenOh, well, you know, I meanOh, my god, my godness, goshyes, no, O.K, right, mm

“It is not always easy, however, to recognise what aclause is. Again, for comparative purposes, the mainrequirement is consistency”(Halliday, 1985, p.67)

Hypotactic clauses:|||Now, I often eat this soup ||when I am tired or worried.||| Paratactic clauses:(Halliday & Mathiessen, 2004; Lukin, 2013)|||Now, I often eat this soup || and it helps me feel better.||||||These students often feel overwhelmed ||and will put off doingmany things they need to.||| Non-defining relative clauses:|||The only Asian country to adopt it at that time was the Philippines,||which the Spanish invaded in the sixteenth century.|||

Defining relative clauses:|| People everywhere appreciate individuals [[who areinterested in getting to know them and learn about their ways ofdoing things]]|| Interrupting clauses||They had to be transported, [[in order to reach safety]],through floodwaters.|| Non-finite clauses(Humphrey et al., 2012; Lukin, 2013)|| [[ To be successful, and to enjoy your experience abroad,]]you must be flexible, open-minded, and both eager and willingto learn new ways of doing things. ||

3. Flesh’s method:How to measure READABILITY?Reading Ease = 206.835 – 0.846 wl – 1.015 sl(Flesch, 1948)Flesch Reading EaseDescription of style0-30 Very difficult30-50 Difficult50-60 Fairly difficult60-70 Standard70-80 Fairly easy80-90 Easy90-100 Very easy

3. Flesh’s method:How to measure READABILITY?Reading Ease = 206.835 – 0.846 wl – 1.015 sl(Flesch, 1948)Flesch Reading EaseDescription of style0-10 Very easy10-20 Easy20-30 Fairly easy30-40 Standard40-50 Fairly difficult50-70 Difficult70-100 Very difficult

ElementaryIntermediatePreintermediateUpperintermediateText 1 Text 2 Text 3 Text 4

Lexical items Total words Ranking clauses Halliday and Ure’s formulas Flesch Reading Ease Scale Correlation(To, V. et al., 2013a)

LEXICAL DENSITY and READABILITY among chosen readingtexts in English textbooksTexts 1(Elementary)2(Preintermediate)3(Intermediate)4(Upperintermediate)Total words 173 160 162 165Lexical words 84 73 61 75Ranking clauses 24 14 15 11LexicaldensityUre’smethodHalliday’smethodFlesch’smethod49% 46% 38% 46%3.5 5.2 4.1 6.825 53 48 44

The changes of LEXICAL DENSITY across levelsFigure 1: Ure's method60%50%49%46%46%40%38%30%20%10%0%Text 1 Text 2 Text 3 Text 4

The changes of LEXICAL DENSITY across levelsFigure 2: Halliday's method86.8765.254.14 3.53210Text 1 Text 2 Text 3 Text 4

The changes of READABILITY across levelsFigure 3: Flesh's method605350484044302520100Text 1 Text 2 Text 3 Text 4

The relationship between LEXICAL DENSITY, READABILITYand TEXT LEVELSLevels Lexical density ReadabilityUre’s methodHalliday’smethodFlesh’s methodElementary the highest the lowest the easiestPre-intermediate high high the mostdifficultIntermediate the lowest high fairly difficultUpper-Intermediatehigh the highest fairly difficult

The correlation between the methods employedTexts Lexical density Correlation coefficientUre’smethodHalliday’smethodFlesch’smethodHalliday &Ure’s methodHalliday &Flesch’smethodFlesh & Ure’smethod1 49 3.5 252 46 5.2 533 38 4.1 484 46 6.8 440.1 0.5 -0.6

Ure’s method revealed that lexical density did notmatch the text levels and text difficulty. In contrast, Halliday’s method of lexical densitycorresponded to the text levels and readability. As for Flesh Reading Ease, readability increased fromlow to high. However, the highest level did not entailthe highest readability.

1. Ure’s method: Lexical density did not match the text levels and text difficulty(Text 1 was the most dense; Text 3 was the least dense).the ILLOGICAL result‣ The texts chosen for the lexical density analysis in the fourbooks may not necessarily represent the complexity for each ofthe books.‣ In this study, the density is only a factor for judgingcomplexity.

2. Halliday’s method: Lexical density corresponded to the text levels and readability.(Text 1 was the least dense; Text 4 was the most dense)Halliday-based findings are LOGICAL‣ It may convince us that Halliday's approach in measuring lexicaldensity is MORE CONSISTENT, thus more powerful.

3. Flesh’s Reading Ease Scale: Readability increased from low to high. However the highest leveldid not entail the highest readability.(Text 2 was the most difficult)‣ Lexical density alone cannot fully explain about readability.

HALLIDAY 'S METHOD is CONSISTENT and applies wellin measuring lexical density in relation to othergrammatical features such as nominalisation,grammatical metaphor, etc. CONSISTENCY is important in analysing lexical density . LEXICAL DENSITY is only ONE ASPECT of textcomplexity. Thus it alone cannot completely explainabout readability.

This is only 'EXPLORATORY‘ study.• The findings support HALLIDAY’S THEORY.• Regarding URE’S METHOD and FLESH READING EASEIt raises more questions than answering .

Sentence structure Nominalisation Grammatical metaphor Thematic structure

Anderson, N. J. (2003). Active Skills for Reading, Books 1 - 4. Boston: Heinle / Cengage.Castello, E. (2008). Text complexity and reading comprehension tests. Bern: Peter Lang. Flesch, R. F. (1948). A New Readability Yardstick. Journal of Applied Psychology, 32, 221-233.Halliday, M. A. K. (1985). Spoken and written language. 1 st ed. [Waurn Ponds], Vic: Deakin University.Halliday, M. A. K., & Matthiessen, C. M. I. M. (2004). An introduction to functional grammar (3rd ed.).London: Arnold.Humphrey, S., Droga, L. & Feez, S. (2012). Grammar and meaning. Newtown: PETAA.Le.T., Yue, Y., & Le, Q. (2011). Linguistic complexity and its relation to language and literacyeducation. New York: Nova Science Publishers, Inc.Lukin, A. (2013). Embedded Clause.: A guide for the confused but conscientious (Lecture). MacquarieUniversity. Retrieved from http://vimeo.com/66871477O'Loughlin, K. (1995). Lexical density in Candidate output on two versions of An oral Proficiency Test.Melbourne Papers in Language Teaching, 26-48.Richards, J. C., Platt, J., & Platt, H. (1992). Longman dictionary of language teaching and appliedlinguistics. London: Longman.To, V., Fan, S. & Thomas, DP. (2013a). Lexical density and Readability: A case study of EnglishTextbooks. The International Journal of Language, Society and Culture, 37(7), 61-71. To, V., Le, T.& Fan, S. (2013b). Different perspectives on linguistic complexity. In T.Le, Q.Le & Fan, S.(Eds), Innovative trends in Language and literacy education in a global discourse. Malaysia: PearsonLongman. (in press)Ure, J. (1971). Lexical density and register differentiation. In G.E. Perren & J.L.M. Trimm(eds). Applications of Linguistics: selected papers of the 2nd International Congress ofApplied Linguists, London: Cambridge University Press, 443-452.

Vinh To - University of TasmaniaVinh.To@utas.edu.auVinh Tô@VinhTTo