PROCESOS DEL SUELO Y SU CAPACIDAD AMORTIGUADORA

The aim of this section is to describe the methodology for creating the first Thai word benchmark dataset, which will be called “TWS-30”. Also, it will present TWS-30 so that it can be used to evaluate the prototype TWSS by calculating and comparing the similarity rating between Human and TWSS in Section 3.4.

3.3.1

Participants

The experiment used 40 participants to provide a safe margin above the group size of 32 which has been sufficient to obtain statistically significant results in prior work (O’Shea et

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al., 2013). In addition, prior work has shown that a diverse group of students can represent the general population (O’Shea et al., 2013).

Similarity ratings were collected from 40 native Thai speakers to create a benchmark dataset. The participants had an equal number of Art/Humanities and Science/Engineering backgrounds. They consisted of 12 undergraduates and 28 postgraduates studying in 4 different UK universities. The average age of the participants was 25 and standard deviation was 2.8, with 23 males and 17 females. The overall breakdown of qualifications was: 45% Bachelor’s degrees; 8% PhDs; 42.5% Master’s. This is comparable with participant groups used for English word similarity by both Rubenstein and Goodenough (1965) and Miller and Charles (1991).

3.3.2

Materials

Following the previous practice of Miller and Charles (1991) and O’Shea et al. (2008), a representative subset of 30 word pairs evenly spread across the similarity range was chosen from the Rubenstein and Goodenough dataset (1965). The original Rubenstein and Goodenough 65 word pair dataset is biased towards low similarity, and so Miller and Charles (1991) selected a subset of 30 word pairs to avoid an inherent bias towards low similarity. The important issue has been raised (O’Shea et al., 2008) that these words are not a representative sample, consisting of largely concrete nouns. However, the set has been widely used in prior word studies (Miller and Charles, 1991; Resnik, 1995; O’Shea et al., 2008). The semantic properties of these words are well understood by researchers in English and this advantage is considered important in creating a Thai dataset at this early stage in the field. Those 30 word pairs were translated into Thai by a native Thai speaker using the first meaning from an established Thai-English dictionary (Trakultaweekoon, 2007). Each word pair was printed on a separate card using a standard Thai font. A questionnaire was produced containing instructions for recording similarity ratings and a small amount of personal data (Name, Confirmation of being a native Thai speaker, Age, Gender, and Academic background) was collected. Semantic anchors were also provided to guide the participants. Appendix 1 contains the following examples of experimental materials:

• Appendix 1.1 The Ethics Statement

• Appendix 1.2 The Instruction Sheet

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• Appendix 1.4 Sample Rating Recording Sheet

• Appendix 1.5 The Person Data Collection Sheet

• Appendix 1.6 Semantic Anchors.

3.3.3

Procedure

The participants were asked to perform the following established procedure (Rubenstein and Goodenough, 1965; Charles, 2000; O’Shea et al., 2008):

1. Please sort the cards into four groups in a rough order of the similarity of meaning of the word pair.

2. After sorting the cards into groups, order the cards in each group according to similarity of meaning (i.e. the card that contains the lowest similarity of meaning is at the top of the group).

3. Please recheck the cards in every group. You may change a word pair to other groups at this stage.

4. Please rate the semantic similarity rating of each pair of words by writing a number between 0.0 (minimum similarity) and 0.9 for the first group, 1.0 and 1.9 for the second group, 2.0 to 2.9 for the third group, 3.0 and 4.0 (maximum similarity) for the fourth group on the recording sheet. You can use the first decimal place (e.g. 2.5) to show finer degrees of similarity. You may also assign the same value to more than one pair.

The cards were shuffled into a random order before being given to the participants. The participants were supervised by the experimenter during the experiment. Previous work (O’Shea et al., 2008) has found no evidence to support the idea of the order of presentation of the sentences in the pair biasing similarity judgment.

3.3.4

TWS-30

The benchmark dataset is shown in Table 3.1. R&G words are the original words from Rubenstein and Goodenough (1965). Translated words are the Thai words translated by Google translation as described in Section 3.2. Column WP shows the number of the word pair of TWS-30. Column Human presents the human rating for the Thai word pairs.

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Table 3.1: The Average of Similarity Rating from 40 Native Thai Speakers

WP

Word Pair

Human

W1 W2

R&G Word Translated

Word R&G Word

Translated Word 1 Cord สายไฟ Smile รอยยิ6ม 0.078 5 Autograph ลายมือชื%อ Shore ชายฝั%ง 0.022 9 Asylum ที%หลบภัย Fruit ผลไม ้ 0.068 13 Boy เด็กผู ้ชาย Rooster นกตัวผู ้ 0.682 17 Coast ฝั%งทะเล Forest ป่าไม ้ 0.632 21 Boy เด็กผู ้ชาย Sage นักปราชญ์ 0.598 25 Forest ป่าไม ้ Graveyard สุสาน 0.548 29 Bird นก Woodland ป่าเขา 0.595 33 Hill เนินเขา Woodland ป่าเขา 2.162 37 Magician นักมายากล Oracle คําทํานาย 1.260 41 Oracle คําทํานาย Sage นักปราชญ์ 1.298 47 Furnace เตาหลอม Stove เตาไฟ 1.613 48 Magician นักมายากล Wizard พ่อมด 1.570 49 Hill เนินเขา Mound ภูเขา 2.420 50 Cord สายไฟ String เชือก 0.882 51 Glass แก ้ว Tumbler ถ ้วยแก ้ว 3.125 52 Grin ยิ6มกว ้าง Smile รอยยิ6ม 2.330 53 Serf ทาส Slave ข ้ารับใช ้ 3.345 54 Journey การเดินทาง Voyage การท่องเที%ยว 2.788 55 Autograph ลายมือชื%อ Signature ลายเซ็น 3.223 56 Coast ฝั%งทะเล Shore ชายฝั%ง 3.218 57 Forest ป่าไม ้ Woodland ป่าเขา 2.830 58 Implement อุปกรณ์ Tool เครื%องมือ 3.335 59 Cock ไก่ตัวผู ้ Rooster นกตัวผู ้ 1.515 60 Boy เด็กผู ้ชาย Lad เด็กหนุ่ม 2.425 61 Cushion เบาะ Pillow หมอน 2.035 62 Cemetery ป่าช ้า Graveyard สุสาน 3.400 63 Automobile รถยนต์ Car รถเก๋ง 3.080 64 Midday เที%ยงวัน Noon กลางวัน 3.008 65 Gem อัญมณี Jewel เพรชพลอย 3.075

3.3.5

Discussion of TWS-30

An appropriate measure of consistency is the correlation coefficient. Similarity measurements have usually been treated as being on a ratio scale in previous word similarity works (Rubenstein and Goodenough, 1965; Miller and Charles, 1991; Resnik, 1999; Charles, 2000). Previous word similarity work has also made the untested assumption that data are normally distributed. However, a recent thorough investigation has established that the English STSS methodology used as the model for this work does produce data suitable for Pearson Product-Moment correlation coefficient (O’Shea et al., 2013). Consequently, the Pearson Product-Moment correlation coefficient (Blalock, 1979) is appropriate.

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Calculating Pearson Product-Moment correlation coefficient between TWS-30 and Rubenstein and Goodenough the result is:

• Pearson’s r = 0.857 (P-Value < 0.01)

For both r, a value of +1 indicates perfect correlation, 0 indicates no relationship and -1 indicates a perfect negative correlation. P-values indicate the likelihood of obtaining the result by chance.

Figure 3.3: Scatter between TWS-30 and R&G

Figure 3.3 shows data points between TWS-30 and R&G. Most of the data points are near the linear line (dotted line). It is quite reasonable not to have a prefect correlation. This is because some of the words are polysemy (the coexistence of many possible meanings for a word) e.g. in English, word ‘glass’ and ‘crane’. The same as Thai, the word ‘แก ้ว’ (glass) means either ‘glass’ or ‘crystal’. It has been conjectured that participants adopt the most similar pair of senses for polysemous words (Rubenstein and Goodenough, 1965). However, there are some data points that are far away from the linear line. The worst data point comes from word pair 50 (Cord-String) top-left in the figure. The word pair 50 (Cord-String) from the R&G English human rating was given as 3.41. Yet, after translation into Thai as ‘สายไฟ-เชือก’, the Thai human rating was given as 0.882. This is because in Thai there is the word ‘สายไฟ’ which has a meaning similar to ‘Cable’ in English. Thus, it

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can be said that Thai humans rate the word pair 50 (Cord-String) according to its meaning in Thai.

3.4

Evaluation of the Thai Word Semantic Similarity