Journal of Science and Technology UTHM The Development of Actual Labour Productivity Measurement Model for Medium-Class Housing in Malang East Java, Indonesia Tjaturono1*, Maziah Ismail2 Department of Civil Engineering, Institut Teknologi Sepuluh Nopember, Surabaya, East Java - Indonesia 1 Faculty of Management Technology, Universiti Tun Hussein Onn Malaysia, Batu Pahat, Malaysia 2 *Corresponding Email: tjaturono@hotmail.com Abstract Up to the moment, the method used for measuring labor productivity in housing construction is the ‘Burgelijke Openbare Werken (BOW) 1921’, its modification, and the Indonesian National Standard (SNI) 2001. However, the labour productivity measured based on these conventional methods does not show the actual on-site productivity. This will make the construction cost estimate inefficient. This research carried out a study on the actual productivity based on eight internal factors and nine external factors, in order to obtain a model for actual labour productivity measurement. The data collection method used was site observation, questionnaires, and interview with the labours in 21 work items in medium-class housing construction in Malang, East Java. Analysis of the main components and multiple regression were applied on the data to obtain the determinants of the productivity model. From this research valid models for labour productivity measurements under the smallest coefficient of determination of 80% were obtained with eight factors strongly affecting the models. Besides, it is also proved that there are quite significant differences between the actual productivities and those of BOW 1921 and SNI 2001. Key words: model, labor productivity, medium-class house, efficient, internal and external factors. 71 chap 6.indd 71 12/21/2009 10:13:46 AM Journal of Science and Technology UTHM 1. INTRODUCTION Among the production factors (labor, land, capital, material, machine, method, etc), labor factor has an important role in achieving a certain productivity level [1,2,3]. Based on the BOW 1921 the labor cost reaches 30-35% of the total construction cost [4,5,6]. Therefore, in facing the competition challenge in the housing industry in Indonesia nowadays, many developers use their own experiences as a reference for the estimate of the production instead of BOW 1921 [7,8,9]. They even revise the legally used government’s standard, the Indonesian National Standard 2001 [10] which has not shown the labor productivity as expected. By using this SNI 2001 the labor cost is still high, which is 23% - 28% of the total construction cost [11]. However, this ‘trial and error’ way of calculation has not given the real productivity either, so that the efficient actual labor cost has not been achieved as yet. Therefore, information on the actual on-site productivity rate is really needed by the developers, since this is one of the key factors to obtain the efficient construction cost of medium-class houses and to increase their competitive power [12,13,14,15,16]. There are many factors which affect labor productivity, internal factors as well as external ones. Suternaister [17] stated that 90% of the labor productivity depends on the labor performance and 10% depends on the technological development and the raw materials. Researches in construction world show that the factors affecting labor productivity are age [18,19], experience [5,18,19], raw material location, height of the brickwork, wage, site condition, labor’s origin [18], building quality [5], education [11,18], supervision, coordination, work sequence, working group composition, facility, overhours work [2], motivation, discipline and skill [11]. Weather condition is a factor affecting productivity too [5,18,20,21], also material supply [5,21,22,23], tools [5,22] and design [2,20]. There are more factors affecting labor productivity according to researchers outside Indonesia, they are accident, disruptions, rework [24], project uniqueness, technology, management [14], information, ability to arrange work sequence [23], overwork schedule [21], work item and construction method [20]. Randolph Thomas stated [25] that there are hardly any researches have been done in housing construction; let alone the modelling of labor productivity in medium-class housing construction, either in or outside Indonesia. Sutikno [18] and Rostiyanti [19] did researches particularly in brickwork, while Kaming et al. [4] did a research on building construction covering soil, masonry foundation, concrete, brick, timber, floor and painting works. Ratnayanti [2] did a research on soil, foundation and concrete works. Particularly in housing construction Tjaturono [11] did a research for 21 work items. As mentioned by Kaming et al [5] the building quality affects the labor productivity, therefore a research on the labor productivity particularly in medium-class housing construction needs to be conducted in order to increase the competitiveness of developers in Indonesia. Based on the experience and the above researches, particularly in medium-class housing construction in Indonesia, the factors need to be studied for their effects on productivity consist of 8 internal factors, namely: age, experience, education, ethnic or labor’s origin, motivation, discipline, skill and health, and 9 external factors, namely: material location, 72 chap 6.indd 72 12/21/2009 10:13:46 AM Journal of Science and Technology UTHM wage, weather, site condition, material supply, tools, coordination & communication, supervisor’s experience and rework. This research was conducted in Malang, since this city has quite a number of developers. There are 34 developers, which is around 25% of the total developers in East Java [26]. The houses in the research are one-story medium-class ones [27,28], while the construction method is a standard one used to be carried out by developers. 2. OBJECTIVES The objectives of this research is to obtain: a. Labor internal and external factors which affect simultaneously and partially the productivity in medium-class housing construction b. Factors which dominantly affect the labor productivity c. The difference between the actual productivity and the productivity based on the conventional methods of BOW 1921 and SNI 2001 d. Labor productivity model affected by the dominant factors 3. RESEARCHMETHODOLOGY The research methodology consists of the following steps: 3.1. Sampling The research covers six medium-class housing developers [26]. Simple random sampling was applied to developers who have built more than 200 medium-class houses. Four developers out of six were selected. This research was done from March, 2004 until August, 2004. Selection of the labor groups of those four developers was based on simple random sampling [29] out of 160 houses of type 70. From each developers 10 groups were taken, so that 40 groups were available for the analysis. Data sufficiency was tested using the formula given by Groeneveld [30] as follows: [ ] 2 Za/2 . S n* = ––––––– , therefore n* = [(1,96 * 0,5724) / 0,184]2 = 36,85. l It shows that the data needed (n*) is smaller than the data available, which are 40 samples, Therefore the samples are sufficient. 73 chap 6.indd 73 12/21/2009 10:13:46 AM Journal of Science and Technology UTHM 3.2. Data collection 3.2.1. Productivity Productivity can be defined as a ratio between the output (achievement) and the input (resources used) or the effectivity and the efficiency [15,31,32], so that: output (achievement) effectivity Productivity = ––––––––––––––––––– or ––––––––––. input (resourcesused) efficiency This means that productivity has two dimensions. First, the effectivity, which is towards the achievement of the maximal performance, that is the achievement related to the quality, quantity and time. The concept of effectivity is based on the output, not the input. Second, the efficiency related to the effort to compare the input with the result of the use of less resources to obtain the same result. So the better the use of the resources is, the higher the efficiency will be. According to Christof [15] there are two measurments of productivity, first is the labor productivity based on output/input ratio approach or single/partial factor productivity or a ratio of output to one of the inputs (labor, capital, etc.); output (achievement) Labor productivity = ––––––––––––––––––– . labor input Second is the multiple-factor productivity, which is the ratio of the total output to several inputs (capital and labor) total output Total productivity = ––––––––––––––––––––––– . total input (labor + capital) This research used the single/partial factor productivity measurement. The productivity resulted from this research will be compared to that of BOW 1921 and SNI 2001. Since the BOW 1921 and SNI 2001 express the productivity in term of labor coefficient, which is the man-day needed to carry out 1 unit of work volume, this coefficient should be tranformed first into productivity (work volume in 1 man-day) by using the following formula: 1 Productivity = –––––––––––––––– . labor’s coefficient The following example on soil excavation work describes the labor productivity measurement according to BOW 1921 [33]. The labors needed to carry out 1 m3 common soil excavation are: 0.75 day worker and 0.025 day supervisor. The figures 0.75 and 0.025 are the worker’s and the supervisor’s coefficients respectively. So the productivity of the worker in soil excavation is 1/0.75 m3 per day. 74 chap 6.indd 74 12/21/2009 10:13:46 AM Journal of Science and Technology UTHM Observation on those 40 working groups were carried out daily for 7 days in the morning, midday and afternoon during the working hours from 7.30 up to 15.30 or 6 effective hours. The measurement of the production is expressed in the production unit/ day/group. 3.2.2. Factors affecting productivity and methods of measurement Data collection was carried out by observation, direct interview and questionnaire. On site observation and questionnaire were carried out to obtain the production of each group for the following qualitative variables: – Skill (SKL), is measured by accuracy, initiative, quick and precise in doing work. Skill categorization: G (good) with score 35- 45; F (fair) with score 25-35; and P (poor) with score 15-25. – Discipline (DSP), is measured by on time, rule obedience, and doing instruction well. DSP categorization: G (good) with score 35- 45; F (fair) with score 25-35; and P (poor) with score 15-25. – Motivation (MTS), is measured by attitude and enthusiasm in doing work productively. MTS categorization: G (good) with score 35- 45; F (fair) with score 25-35; and P (poor) with score 15-25. Scoring for skill, discipline, and motivation are determined by these following steps: 15 items of questionnaire which set using Likert scale. To score the scale, the response categories must weighted, with the numeric values 1, 2, and 3 respectively are assigned to the response categories. Sugiono [34] are answered by each mason. The sum of the weights of all items would represent the individual’s total score: G (good): 35-45; Fair (2535); and Poor (15-25). The highest score is 45, the middle score is 30, and the lowest is 15, with range 10 for each category. – Material supply (MS) is measured by timely in preparing materials MS categorization is G (good) = often on time, F (fair)= almost on time, P (poor) = often too late. – Health (HTH), is measured by physical appearance, not handicapped, and having good sense organs. HTH categorization is G = healthy, not handicapped, good physical appearance F = somewhat healthy, handicapped but able to work well; P = unhealthy, handicapped and the productivity is less than average. – Communication and Coordination (CC), is measured by information accuracy and fluency from the manager to the labor. 75 chap 6.indd 75 12/21/2009 10:13:46 AM Journal of Science and Technology UTHM CC Categorization: G = fluent and accurate information, F: adequate information; P = information is almost unavailable. – Rework (RW) is measured by the amount of works which are repeated. RW Categorization: G = no work repeated work, F = work is sometimes repeated work, P = work is often repeated. – Site (St), is measured by the in situ real condition or there is no puddle of water St Categorization G = dry, F= wet, and P = muddy. – Tool (TL) is measured by how complete is the tools brought by a mason. TL Categorization: G = complete tools, F= incomplete tools, P= shortcomings of tools. – Education (EDU), is measured by level of formal education. EDU Categorization = Primary School, Junior High School, and Senior High School. Direct interview and observation to the labors/labor groups are conducted for the following quantitative variables: – Experience (EXP), is measured by the length of experience and measured in year. EXP Categorization: less than 5 years, from 5 to 10 years, and more than 10 years. – Age (AGE), is measured by the length of living AGE Categorization: less than 20 years, from 20 – 30 years, more than 30 years. – Material location (MD), is measured by distance between materials and location of work. MD Categorization: less than 5 meters, from 5 – 10 meters, and more than 10 meters. – Weather Condition (W), is measured by the temperature in the location of work W Categorization: less than 25º C, from 25- 30º C, and more than 30º C – Wage (WG), is measured by the amount of money received by a labor. WG Categorization: Rp. 30.000; Rp. 27.500, and Rp. 25.000 – Supervisor experience (SE), is measured by the length of supervising is conducted. SE Categorization: less than 5 years, from 5 – 10 years, and more than 10 years. 3.3. Data grouping and their scales The data obtained from 21 work items are classified based on some characteristics and measurements, with the following scales: 76 chap 6.indd 76 12/21/2009 10:13:46 AM Journal of Science and Technology UTHM – Rational, for experience (years), age (years), material location (m), weather/ temperature (C), wage (Rp), and supervisor’s experience (years) – Ordinal to interval with Internal Successive Method [35] for education, skill, discipline, motivation, health, rework, material supply, site condition, communication and coordination and tools (Table 1). – Nominal: for ethnic. 3.4. Statistical method The statistical method used consists of descriptive statistics, correlation, factor analysis and multiple regression analysis. Before carrying out the factor analysis it is necessary to define the number of factors properly representing the variable groups by using main component analysis. The number of factors was decided based on the number of Eigen values which are more than 1 [36]. The productivity model obtained from the analysis was then tested for its validity by checking whether the assumptions defined as the requirements for the application of regression analysis method are satisfied or not. The assumptions to be satisfied are that the residuals of the regression equation are identical (the variances are uniform), independent (no correlation among the residuals) and normally distributed. Whether the first assumption was satisfied or not can be shown by the plot between the residuals and the predicted responses calculated based on the model. If the plot does not show the behavior as shown by [37], then it can be concluded that the variances of the residuals are uniform. The satisfaction of the second assumption can be proved by carrying out a test on whether there is a serial autocorrelation among the residuals or not. The testing procedure is given by Draper and Smith [37] by comparing the Durbin-Watson statistics to the limit of the refusal area. While the third assumption test was carried out by residual normal plotting and Kolmogorov-Smirnov test. 4. DATAANALYSISANDDISCUSSION In order to show the steps in developing the model, out of 21 work items one is selected as an example, namely masonry foundation. Discrete data of the masons used for the calculation and analysis with the new scales are shown in Table 1. From the data in Table 1 a descriptive statistics of all variables was obtained as shown in Table 2. It can be seen in this table that the average mason productivity in a day is 3.69 m3, the standard deviation is 0.5724 m3, the productivity range is 1.7 m3 with the lowest productivity is 2.8714 m3 and the highest one 4.5724 m3. 77 chap 6.indd 77 12/21/2009 10:13:47 AM Journal of Science and Technology UTHM Table 1. Productivity data of masons in masonry foundation with new scales (rational and interval) NO chap 6.indd 78 NAME MtS MD W St Wg SE CC RW TL EXP AGE EDU DSP MTV ETC HTH SKL AVE PRDCTV 1 Sutrisno 2.290 10 25 3.944 27.5 8 2.133 3.795 2.264 10 32 1.000 2.392 2.297 Jw 2.624 2.129 3.6929 2 Maun 2.290 10 30 2.476 25 8 2.133 2.375 1.000 14 36 1.000 2.392 2.297 M 2.624 2.129 3.3714 3 Tomy 2.290 5 25 2.476 30 8 2.133 3.795 3.572 7 26 2.822 3.802 3.624 Jw 2.624 3.359 4.4714 4 Sanapi 2.290 8 28 2.476 25 8 2.133 2.375 2.264 10 35 1.000 2.392 2.297 M 1.000 2.129 3.4714 5 Martoyo 3.666 8 28 2.476 27.5 4 2.133 3.795 2.264 15 40 1.000 2.392 2.297 Jw 1.000 2.129 3.6214 6 Buasim 2.290 10 32 2.476 25 4 1.000 2.375 2.264 4 26 1.000 2.392 1.000 M 2.624 1.000 3.0500 7 Yasin 2.290 10 32 1.000 25 4 1.000 1.000 1.000 2 23 1.000 2.392 1.000 M 1.000 1.000 2.8786 8 Nurali 1.000 14 28 2.476 25 4 1.000 2.375 2.264 8 28 1.000 2.392 2.297 M 1.000 2.129 3.1429 9 Husen 1.000 8 30 1.000 27.5 8 2.133 2.375 1.000 2 26 1.000 1.000 2.297 M 1.000 1.000 2.9286 10 Suwono 2.290 14 25 2.476 27.5 8 2.133 2.375 2.264 7 30 1.000 2.392 2.297 Jw 2.624 2.129 3.2071 11 Sugeng A 3.666 10 24 3.944 30 8 2.133 3.795 3.572 6 26 1.000 2.392 2.297 Jw 2.624 3.359 4.0571 12 Samaun 2.290 10 24 3.944 30 8 3.388 2.375 3.572 10 30 1.000 2.392 2.297 Jw 1.000 3.359 4.0000 13 Tukimin 3.666 8 23 3.944 30 12 3.388 3.795 3.572 10 32 2.822 3.802 3.624 Jw 2.624 3.359 4.2429 14 Sugeng B 3.666 8 23 2.476 30 12 3.388 2.375 3.572 10 28 2.822 3.802 3.624 Jw 1.000 3.359 4.2143 15 Mat Supi'I 3.666 10 30 2.476 27.5 12 3.388 2.375 2.264 6 24 1.000 2.392 2.297 M 1.000 2.129 3.6143 16 Sapit 3.666 14 24 2.476 30 12 3.388 3.795 3.572 12 30 1.000 3.802 3.624 Jw 1.000 3.359 4.2429 17 Suroso 2.290 14 23 2.476 30 12 3.388 3.795 2.264 10 30 1.000 3.802 3.624 Jw 2.624 3.359 4.3000 18 Martono 2.290 5 28 2.476 25 12 3.388 2.375 1.000 8 26 1.000 1.000 1.000 Jw 2.624 1.000 2.9714 19 Husin 3.666 8 28 3.944 30 12 3.388 3.795 2.264 8 28 1.000 3.802 2.297 M 2.624 3.359 4.3286 20 Mulyono 3.666 8 28 2.476 27.5 12 3.388 3.795 2.264 5 26 1.000 2.392 2.297 Jw 2.624 2.129 3.4714 21 Rewok 3.666 7 25 2.476 30 12 3.388 3.795 3.572 8 28 1.000 3.802 3.624 Jw 2.624 3.359 4.4286 22 Basori 3.666 7 25 2.476 30 12 3.388 2.375 2.264 6 27 2.822 3.802 2.297 Jw 1.000 3.359 4.2286 23 Bakir 2.290 4 24 2.476 27.5 4 2.133 2.375 2.264 6 26 1.000 2.392 2.297 M 2.624 2.129 3.5143 24 Hartono 2.290 4 24 2.476 25 4 2.133 1.000 1.000 7 30 1.000 1.000 1.000 Jw 1.000 1.000 2.9143 25 Buasin 3.666 14 26 2.476 30 4 2.133 3.795 2.264 14 38 1.000 3.802 3.624 M 1.000 3.359 4.2714 26 Sugeng 2.290 8 25 4 2.133 2.375 2.264 2 20 1.000 2.392 1.000 Jw 2.624 1.000 2.9143 27 Basuki 2.290 10 26 1.000 27.5 8 3.388 2.375 3.572 12 35 1.000 2.392 2.297 Jw 2.624 2.129 3.5000 28 Saturi 2.290 6 24 2.476 30 8 3.388 3.795 3.572 15 38 1.000 3.802 3.624 Jw 2.624 3.359 4.4286 29 Nurali 3.666 6 24 2.476 30 8 3.388 3.795 3.572 10 33 2.822 3.802 3.624 Jw 1.000 3.359 4.5000 30 Suwono 3.666 10 26 2.476 25 8 3.388 2.375 2.264 8 28 1.000 2.392 2.297 Jw 2.624 2.129 3.4429 31 Rodat 3.666 10 28 3.944 27.5 10 2.133 2.375 2.264 5 30 1.000 2.392 2.297 M 2.624 2.129 3.5286 32 Manu 3.666 8 28 2.476 27.5 10 2.133 2.375 1.000 4 25 1.000 2.392 2.297 Jw 2.624 2.129 3.5429 33 Nasim 2.290 5 24 3.944 30 10 2.133 3.795 2.264 20 45 2.822 3.802 3.624 Jw 2.624 3.359 4.5714 34 Warsim 2.290 5 24 3.944 30 10 2.133 3.795 3.572 20 47 1.000 3.802 3.624 Jw 1.000 3.359 4.5286 35 Sukaeri 3.666 8 28 2.476 27.5 4 1.000 2.375 2.264 6 30 1.000 2.392 2.297 Jw 2.624 2.129 3.5571 36 Huda 3.666 8 28 2.476 25 4 1.000 1.000 2.264 5 29 1.000 2.392 1.000 Jw 2.624 1.000 2.9000 37 Hadi 1.000 14 28 1.000 27.5 4 1.000 2.375 1.000 10 30 1.000 2.392 2.297 Jw 2.624 2.129 3.2143 38 Gimin 1.000 10 30 1.000 25 4 1.000 2.375 2.264 5 26 1.000 1.000 1.000 Jw 2.624 1.000 2.8714 39 P. Nur 2.290 10 30 2.476 27.5 12 3.388 3.795 3.572 7 32 1.000 2.392 2.297 M 2.624 2.129 3.3286 40 Turiman 2.290 4 30 12 3.388 3.795 3.572 8 30 1.000 3.802 3.624 Jw 2.624 3.359 4.3714 30 1.000 26 2.476 78 12/21/2009 10:13:47 AM 26 Sugeng 2.290 8 27 Basuki 2.290 10 26 1.000 30 1.000 25 4 2.133 2.375 2.264 2 20 1.000 2.392 1.000 Jw 2.624 1.000 2.9143 27.5 8 3.388 2.375 3.572 12 35 1.000 2.392 2.297 Jw 2.624 2.129 3.5000 28 Saturi 2.290 6 24 2.476 30 8 3.388 3.795 3.572 15 38 1.000 3.802 3.624 Jw 2.624 3.359 4.4286 29 Nurali 3.666 6 30 Suwono 3.666 24 2.476 30 8 3.388 3.795 3.572 10 33 2.822 3.802 3.624 Jw 1.000 3.359 4.5000 10 26 2.476 25 8 3.388 2.375 2.264 8 28 1.000 2.392 2.297 Jw 2.624 2.129 3.4429 31 Rodat 3.666 10 28 3.944 27.5 10 2.133 2.375 2.264 5 30 1.000 2.392 2.297 M 2.624 2.129 3.5286 32 Manu 33 Nasim 3.666 8 28 2.476 27.5 10 2.133 2.375 1.000 4 25 1.000 2.392 2.297 Jw 2.624 2.129 3.5429 2.290 5 24 3.944 30 10 2.133 3.795 2.264 20 45 2.822 3.802 3.624 Jw 2.624 3.359 4.5714 34 Warsim 2.290 5 24 3.944 Journal Science and Technology 30 10 of 2.133 3.795 3.572 20 UTHM 47 1.000 3.802 3.624 Jw 1.000 3.359 4.5286 35 Sukaeri 3.666 8 28 2.476 27.5 4 1.000 2.375 2.264 36 Huda 3.666 8 28 2.476 25 4 1.000 1.000 37 Hadi 1.000 14 28 1.000 27.5 4 1.000 2.375 38 Gimin 1.000 10 30 1.000 25 4 1.000 39 P. Nur 2.290 10 30 2.476 27.5 40 Turiman 2.290 4 30 26 2.476 6 30 1.000 2.392 2.297 Jw 2.624 2.129 3.5571 2.264 5 29 1.000 2.392 1.000 Jw 2.624 1.000 2.9000 1.000 10 30 1.000 2.392 2.297 Jw 2.624 2.129 3.2143 2.375 2.264 5 26 1.000 1.000 1.000 Jw 2.624 1.000 2.8714 12 3.388 3.795 3.572 7 32 1.000 2.392 2.297 M 2.624 2.129 3.3286 12 3.388 3.795 3.572 8 30 1.000 3.802 3.624 Jw 2.624 3.359 4.3714 Table 2. Descriptive Statistics of Masons in Masonry Foundation Work Variable MtS MD W St Wg SE CC RW TL EXP AGE EDU DSP MTV HTH SKL AVE PR N Mean Median StDev Minimum Maximum 40 2.746 2.2900.885 1.000 3.666 40 8.750 8.000 2.933 4.000 14.000 40 26.650 26.000 2.597 23.000 32.000 40 2.548 2.476 0.878 1.000 3.944 40 27.813 27.500 2.056 25.000 30.000 40 8.200 8.0003.196 4.000 12.000 40 2.468 2.133 0.895 1.000 3.388 40 2.875 2.375 0.876 1.000 3.795 40 2.468 2.264 0.903 1.000 3.572 40 8.5508.000 4.266 2.000 20.000 40 30.225 30.0005.582 20.000 47.000 40 1.273 1.000 0.659 1.000 2.822 40 2.746 2.3920.885 1.000 3.802 40 2.468 2.2970.902 1.000 3.624 40 2.056 2.6240.785 1.000 2.624 40 2.395 2.129 0.900 1.000 3.359 40 3.6959 3.5500 0.5724 2.8714 4.5714 In order to check whether there is no autocorrelation nor multicollinearity among the independent variables, it is necessary to identify the relations among these variables by checking the correlation between pairs of all the variables as seen in Table 3. From Table 3 it is seen that there are strong autocorrelations among some of the variables, which is shown by p-value less than 0.05. This shows an interdependence among the variables so that the model development between the variable productivity and the variables which were presumed as affecting can not be carried out directly. Whilst, the correlations between the productivity and almost all of the independent variables are quite significant except the variables: material distance (MD) and health (HTH). However, the variable MD can still be included in the model, since it has a valid correlation with the variable education. The model was then formulated by grouping the independent variables having strong correlations to form certain factors. Based on the main component analysis the ideal number of factors was obtained as 4 factors as shown in Table 4 with their respective Eigen value 7.2176, 1.8660, 1.2316 and 1.1491. Then factor analysis using maximum likelihood method and varimax rotation, as shown in Table 5, shows that factor 1 was formed by the variables: material 79 chap 6.indd 79 12/21/2009 10:13:48 AM Journal of Science and Technology UTHM supply (loading factor 0.565), weather (-0.578), wage (0.830), supervisor’s experience (0.770), communication and coordination (0.776), rework (0.674), tools (0.684), discipline (0.756), motivation (0.744) and skill (0.834). Factor 2 was formed by the variables: experience (-0.918) and age (-0.937), while factor 3 by the variable material distance (-0.900), and factor 4 by the variable health (0.830). Loading factor for the variable skill is 0.834 which means that this variable has a strong correlation with Factor 1. The variables which form the respective factors can also bee seen in Fig. 1. Table 3. Matrix of Correlation between Independent and Dependent Variables MtS MD W S Wg SE CC MD -0.096 0.555 W -0.244 0.180 0.130 0.266 St 0.412 -0.169 -0.485 0.008 0.298 0.002 Wg 0.350 -0.104 -0.687 0.457 0.027 0.524 0.000 0.003 SE 0.357 -0.137-0.325 0.398 0.537 0.024 0.400 0.041 0.011 0.000 CC 0.402 -0.187 -0.465 0.252 0.532 0.800 0.010 0.248 0.003 0.1170.0000.000 RW 0.217 -0.037-0.416 0.436 0.715 0.478 0.465 0.178 0.819 0.008 0.005 0.000 0.002 0.002 TL 0.276 -0.109-0.536 0.348 0.637 0.355 0.475 0.084 0.504 0.000 0.028 0.000 0.024 0.002 EXP 0.012 -0.052 -0.496 0.392 0.426 0.161 0.215 0.942 0.749 0.001 0.012 0.006 0.321 0.182 AGE -0.011 -0.106 -0.362 0.381 0.323 0.0460.057 0.944 0.515 0.022 0.015 0.042 0.777 0.727 EDU 0.222 -0.326 -0.434 0.202 0.453 0.284 0.238 0.169 0.040 0.005 0.211 0.003 0.076 0.139 DSP 0.414 -0.050 -0.541 0.375 0.780 0.434 0.413 0.008 0.758 0.000 0.017 0.000 0.005 0.008 MTV 0.248 -0.037 -0.666 0.359 0.835 0.502 0.485 0.123 0.820 0.000 0.023 0.000 0.001 0.002 HTH-0.040 -0.063 0.063 0.062 -0.081 0.080 -0.034 0.805 0.698 0.698 0.704 0.621 0.625 0.835 SKL 0.378 -0.031 -0.722 0.543 0.910 0.533 0.545 0.016 0.851 0.000 0.0000.000 0.000 0.000 0.583 0.000 0.496 0.001 0.414 0.008 0.217 0.179 0.623 0.000 0.735 0.000 0.161 0.321 0.717 0.000 AVEPRDTV 0.406 -0.203 -0.702 0.009 0.210 0.000 0.751 0.000 0.544 0.000 0.914 0.537 0.542 0.000 0.000 0.000 RW 80 chap 6.indd 80 12/21/2009 10:13:48 AM Journal of Science and Technology UTHM TL EXP AGE EDU DSP MTV HTH EXP 0.316 0.047 AGE 0.247 0.920 0.124 0.000 EDU 0.315 0.194 0.123 0.048 0.2290.451 DSP 0.609 0.482 0.363 0.507 0.000 0.002 0.021 0.001 MTV 0.603 0.598 0.494 0.441 0.817 0.000 0.0000.001 0.004 0.000 HTH 0.006 -0.153-0.151 -0.132 -0.043-0.097 0.9700.3460.353 0.416 0.792 0.552 SKL 0.671 0.558 0.410 0.456 0.863 0.885 -0.088 0.0000.0000.0090.003 0.000 0.000 0.588 AVEPRDTV0.661 0.000 0.582 0.000 0.453 0.003 0.502 0.001 0.888 0.000 0.888 -0.076 0.000 0.643 SKL 0.961 0.000 CellContents:Pearsoncorrelation P-Value Loading Plot of P.Mt-KTRP 0.5 W MtS MD HTH CC Second Factor 0.0 EDU TL RW ST -0.5 DSP MTV AGE -1.0 -0.5 0.0 WG SKL EXP 0.5 First Factor Figure 1. Loading Plot of variable MtS – SKL Table 4. Main Component Analysis for Eigen Value Calculation from the Correlation Matrix Eigenanalysis of the Correlation Matrix Eigenvalue 7.2176 1.8660 1.2316 1.1491 0.9683 0.8797 Proportion 0.451 0.117 0.077 0.072 0.061 0.055 Cumulative 0.451 0.568 0.645 0.717 0.777 0.832 81 chap 6.indd 81 12/21/2009 10:13:48 AM Journal of Science and Technology UTHM Table 5. Factor Analysis on Independent Variables Principal Component Factor Analysis of the Correlation Matrix Rotated Factor Loadings and Communalities Varimax Rotation Variable Factor1 Factor2 Factor3 Factor4 Communality MtS 0.5650.165 0.231-0.009 0.399 MD -0.0190.062-0.900-0.056 0.817 W -0.5780.435 -0.2440.174 0.614 St 0.422 -0.415 0.3260.263 0.526 Wg 0.830-0.357 0.027-0.146 0.838 SE 0.7700.067 0.1540.217 0.669 CC 0.7760.064 0.1600.087 0.639 RW 0.674-0.478 -0.1190.251 0.759 TL 0.684 -0.2700.014-0.035 0.542 EXP 0.182 -0.918 0.027-0.079 0.882 AGE 0.023 -0.937 0.078-0.044 0.886 EDU 0.425-0.093 0.490 -0.464 0.644 DSP 0.756-0.381 -0.009-0.207 0.760 MTV 0.744-0.5240.066-0.180 0.864 HTH 0.0350.060 0.048 0.830 0.696 SKL 0.834-0.458 -0.010-0.146 0.927 Variance 5.67193.1925 1.34761.2523 11.4642 % Var 0.3540.200 0.0840.078 0.717 Table 6. Factor Score Coefficients FactorScoreCoefficients Variable Factor1 Factor2 Factor3 Factor4 MtS 0.155 0.1770.121 -0.012 MD 0.107 0.039-0.725 -0.070 W -0.046 0.080-0.133 0.096 St 0.003 -0.1380.225 0.265 Wg 0.152 0.002-0.071 -0.081 SE 0.203 0.1510.041 0.185 CC 0.202 0.1620.042 0.078 RW 0.109 -0.115-0.162 0.254 TL 0.131 0.005-0.064 0.002 EXP -0.123 -0.378 0.010 0.017 AGE -0.174 -0.4190.069 0.047 EDU 0.036 0.0700.338 -0.362 DSP 0.131 -0.017-0.093 -0.131 MTV 0.109 -0.086-0.135 -0.098 HTH 0.023 -0.0390.051 0.684 SKL 0.139 -0.043-0.101 -0.073 82 chap 6.indd 82 12/21/2009 10:13:48 AM Journal of Science and Technology UTHM From the factor analysis it is also obtained the factor scores for the four factors which will replace the original independent variables as new variables in the regression analysis. By using the values of factor score coefficients as shown in Table 6, the factor scores were obtained from the respective factor as shown in Equation 1. Factor1=0.155MtS+0.107MD-0.046W0.003St+0.152Wg+0.203SE +0.202CC+0.109RW+0.131TL-0.123EXP-0.174AGE +0.036EDU+0.131DSP+0.109MTV+0.023HTH+0.139 SKL Factor2=0.177MtS+0.039MD+0.08W+0.138St+0.002Wg+ 0.151SE+0.162CC-0.115RW+0.005TL-0.378EXP -0.419AGE+0.07EDU-0.017DSP-0.086MTV-0.039HTH -0.043SKL Factor3=0.121MtS-0.725MD-0.133W+0.225St-0.071Wg+ 0.041 SE + 0.042 CC -0.162 RW -0.064 TL + 0.01 EXP 0.069AGE+0.338EDU-0.093DSP-0.135MTV+0.051 HTH-0.101SKL Factor4=-0.012MtS-0.07MD+0.096C+0.265St-0.081Up+ 0.185PP+0.078CC+0.254+U+0.002TL+0.017EXP +0.047AGE-0.362EDU-0.131DSP-0.098MTV+0.684 HTH-0.073+SKL (E.1) (E.1) Then Factor 1, Factor 2, Factor 3 and Factor 4 together with the variable ethnic (ETC) become independent variables in the regression analysis. Variable ETC is not included as one of the forming factors since it has a nominal scale and in the regression analysis this variable is a dummy one which has the value of 0 (Maduranese) or 1 (Javanese). In the regression model development between the variable productivity and the variables ETC, Factor 1, Factor 2, Factor 3 and Factor 4 it is first selected which independent variables should be included in the model. This variable selection was carried out by using stepwise method [37] with the a value of 5% for the independent variables to be in and out of the model. Based on the stepwise method the independent variables or factors that should be included in the model are Factor 1, Factor 2, Factor 3 and Factor 4 with the variable/factor sequence priority as seen in Table 7. While the variable ETC does not satisfy the criterium to become one of the independent variables in defining the regression model of mason. By using regression analysis, the calculation result for obtaining the relationship between the variable productivity and Factor 1, Factor 2, Factor 3 and Factor 4 can be seen in Table 8. The regression equation expressing the productivity of mason is as follows: Productivity=3.70+0.465FACTOR1-0.278FACTOR2 (E.2) +0.0751FACTOR3-0.0743FACTOR4 83 chap 6.indd 83 12/21/2009 10:13:48 AM Journal of Science and Technology UTHM Table 7. Result of the Variable Selection by Stepwise Method Alpha-to-Enter: 0.05 Alpha-to-Remove: 0.05 Response is AVE PR on 5 predictors, with N = 40 Step 1 Constant 3.696 2 3.696 FACTOR1 0.465 0.465 T-Value 8.57 15.28 P-Value 0.000 0.000 FACTOR2 -0.278 T-Value -9.16 P-Value 0.000 FACTOR3 T-Value P-Value FACTOR4 T-Value P-Value S 0.339 0.190 R-Sq 65.91 89.56 R-Sq(adj) 65.01 89.00 C-p 130.5 17.0 3 3.696 4 3.696 0.465 0.465 16.50 18.11 0.000 0.000 -0.278 -0.278 -9.88 -10.85 0.000 0.000 0.075 0.075 2.67 2.93 0.011 0.006 -0.074 -2.90 0.006 0.176 0.160 91.28 92.97 90.56 92.16 10.6 4.4 Tests on the coefficients show that each coefficient of the four factors is significant (p-value << 0,05). The significant results are also expressed by the regression equation as shown by the variance analysis in Table 9. The four factors can describe the variation in the productivity as much as 92.97% (R2). While the percentage of variation which can be described by the regression equation obtained after the calculation adjustment related to the free degree between the square sum of the residuals and the square sum of the corrected total [37] is 92.16% (R2 adj). Table 8. Result of Regression Analysis between the Variable Productivity and Factor 1 – Factor 4. Theregressionequationis AVEPRDCTV=3.70+0.465FACTOR1-0.278FACTOR2+0.0751FACTOR3- 0.0743FACTOR4 PredictorCoef SECoefT P VIF Constant3.69589 0.02533145.89 0.000 FACTOR10.46471 0.0256618.11 0.000 1.0 FACTOR2-0.27836 0.02566-10.85 0.000 1.0 FACTOR30.07510 0.025662.93 0.006 1.0 FACTOR4-0.07433 0.02566-2.90 0.006 1.0 S=0.1602 R-Sq=93.0% R-Sq(adj)=92.2% 84 chap 6.indd 84 12/21/2009 10:13:48 AM Journal of Science and Technology UTHM Table 9. Variance Analysis of Regression Equation AnalysisofVariance Source DF SS MS F P Regression 4 11.8794 2.9699 115.68 0.000 ResidualError 35 0.8985 0.0257 Total 39 12.7779 For model validation, whether the assumption that the residuals of the regression equation is identical (the variances are uniform), the test result shows that the residuals tend to be constant (Figure 3), which means that the assumption is satisfied. Plot Residual Vs Response Predicted S ta n d a r d i z e d R e s i d u a l 0, 3 0, 2 0, 1 0 0 5 10 15 20 25 30 35 40 -0, 1 45 F IT S1 -0, 2 -0, 3 -0, 4 Response Predicted Figure 3. Plot of Standardized Residual Vs Predicted Response In testing whether there is a serial correlation among the residuals, the calculation result shows that the Durbin-Watson statistics is 2.49, while the table value of a = 5% with 4 independent variables on two-side test is dl = 1,29. Because d = 2,49 > dl or 4 – d > dl then it can be concluded that there is no serial autocorrelation among the residuals. The third assumption can be satisfied by the assumed model using KolmogorovSmirnov normality test where p-value > 0.15 which means H0 is accepted or it is proved that the residuals follow the normal distribution. This can also be seen on the plot of the residuals on the normal paper in Fig. 4 as follows. 85 chap 6.indd 85 12/21/2009 10:13:48 AM Journal of Science and Technology UTHM Normal Probability Plot .9 9 9 .9 9 Probability .9 5 .8 0 .5 0 .2 0 .0 5 .0 1 .0 0 1 -0.3 A verage: -0.0000000 S tDev: 0.151787 N: 40 -0.2 -0.1 0.0 0.1 0.2 K olm ogorov-S m irnov Norm ality Tes t D+ : 0.059 D-: 0.074 D : 0.074 A pprox im ate P -V alue > 0.15 Resi 1 Figure 4. Plot of Residual Normal Probability For the interpretation the equation (e.2) has to be returned to the original variable so that the role of each variable forming the factors will be known. By replacing Factor 1, Factor 2, Factor 3 and Factor 4 in equation (e.2) with equations (e.1), we will obtain equation (e.3) which states the direct relations between the internal and external variables and the variable productivity for mason. Productivity=3.70+0.0327MtS-0.0102MD-0.0605W + 0.0369 St + 0.07085 Wg + 0.04161 SE +0.04615CC+0.05146RW+0.05473TL +0.04747EXP+0.03743AGE+0.04962EDU +0.06856 DSP+ 0.07153 MTV -0.02533 HTH +0.07442SKL (E.3) Based on the equation (e.3) the average productivity of mason can be predicted as much as 3.70 m3 per day. The variables having positive contribution to the productivity increase is material supply (MtS), site (St), wage (Wg), supervisor’s experience (SE), communication and coordination (CC), rework (RW), tools (Tl), experience (EXP), age (AGE), discipline (DSP), motivation (MTV) and skill (SKL). The biggest contribution is given by the variables: skill (0,07442), motivation (0,07153), wage (0,07085) and dicipline (0,06856). While the variables having negative contribution are: material distance (MD), weather (W) and health (HTH). The biggest negative contribution is given by the variable weather for rock foundation work item. This procedure can be repeated to develop the models of the other 20 work items. Table 10 shows the whole predicted model equations for 21 work items. In general for 21 work items, the variables such as material supply (MtS), site condition (St), wage (Wg), supervisor’s experience (SE), communication and 86 chap 6.indd 86 12/21/2009 10:13:48 AM chap 6.indd 87 Work item IntSep Const. MtS MD W St Wg SE CC RW TL EXP AGE EDU DSP MTV HTH SKL R2 (%) 3.7000 0.0327 -0.0102 -0.0605 0.0369 0.0709 0.0416 0.0461 0.0515 0.0547 0.0475 0.0374 0.0496 0.0686 0.0715 -0.0253 0.0744 93.0 7 Masonry 84.79 85.1 84.4 91.1 90.6 21 Wall painting 18.3821 0.3022 -0.0173 0.0596 0.1342 0.3431 0.0778 0.3624 0.3597 0.2961 0.1694 0.1325 0.1139 0.3797 0.3861 0.0861 0.3991 92.0 91.4 88.2 79.7 90.5 Floor tile 13.7286 0.1278 0.0229 -0.0285 0.0960 0.1365 0.1067 0.1446 0.1466 0.1317 0.0196 0.0264 0.1072 0.1550 0.1582 0.0597 0.1429 91.4 installation Door & window 19 leaf 3.0979 0.0422 -0.0185 -0.0132 -0.0039 0.0302 0.0012 0.0370 0.0444 0.0447 -0.0061 -0.0103 -0.0194 0.0429 0.0335 0.0067 0.0357 80.2 installation Timber 20 5.7386 0.0042 0.0397 0.0279 0.0384 0.0865 -0.0529 0.0687 0.1023 0.1009 -0.0114 -0.0177 0.0796 0.1165 0.1205 -0.0183 0.1189 88.8 painting 18 89.3 17 Ceiling work 11.7643 0.2561 -0.0290 -0.0118 -0.0317 0.1751 -0.0536 0.2660 0.2787 0.2857 0.0534 0.0238 0.0377 0.2723 0.2588 0.1694 0.2260 91.5 15.5000 0.0707 -0.0690 0.0493 0.0469 0.1376 0.0549 0.1650 0.1515 0.2044 0.0781 0.0590 0.0600 0.1806 0.1936 0.0318 0.1948 90.4 21.2179 0.1631 -0.0138 -0.1172 0.1027 0.3989 0.1118 0.3465 0.3288 0.3828 0.1628 0.0885 0.2004 0.3609 0.4419 0.0845 0.4484 87.88 87.23 27.6679 0.4993 -0.1530 0.1920 -0.0392 0.4697 0.2533 0.3723 0.3781 0.5121 0.0507 0.0714 0.2312 0.5028 0.4728 0.4528 0.4700 86.6 0.2080 0.0029 -0.0027 0.0018 0.0003 0.0030 0.0009 0.0060 0.0058 0.0058 0.0001 -0.0005 -0.0007 0.0068 0.0059 0.0034 0.0047 88.2 87.1 Rafter and batten work Roof tile installation Wall rendering Molding plaster Electrical & plumbing 1.3757 0.0095 -0.0014 0.0142 0.0056 0.0194 0.0137 0.0184 0.0199 0.0180 0.0066 0.0051 0.0110 0.0167 0.0189 0.0086 0.0197 92.3 85.8 93.0 92.2 88.0 94.0 85.8 84.9 94.1 88.3 R2 adj (%) 5.0750 0.0793 -0.0255 0.0527 0.0530 0.0795 0.0441 0.0760 0.0719 0.0961 0.0211 0.0246 0.1121 0.1096 0.1045 -0.0210 0.0917 88.1 16 15 14 13 12 11 Brick work Concrete 8 1.1661 0.0063 -0.0024 -0.0006 0.0100 0.0189 0.0150 0.0198 0.0190 0.0222 -0.0021 -0.0024 0.0158 0.0210 0.0218 0.0085 0.0241 93.9 pouring Timber frame 9 0.4121 0.0063 0.0049 0.0055 -0.0023 0.0069 0.0034 0.0039 0.0093 0.0103 0.0011 0.0006 0.0027 0.0119 0.0111 -0.0009 0.0094 86.9 installation Roof truss & 10 0.2694 0.0033 -0.0027 -0.0009 0.0000 0.0034 -0.0016 0.0034 0.0042 0.0032 0.0011 0.0007 0.0002 0.0041 0.0031 0.0012 0.0039 purlin work 89.7 48.4670 0.3655 -0.1874 0.1009 0.0538 0.6147 0.6250 0.7383 0.8603 0.9038 0.1732 0.1528 0.3838 0.8109 0.8472 0.5585 0.9215 89.2 6 Form work Timber frame 0.1158 0.0014 0.0009 -0.0012 0.0012 0.0019 0.0003 0.0012 0.0011 0.0013 0.0005 0.0003 0.0017 0.00170.0017 0.0007 0.0022 86.5 Door & window 4 6.0979 -0.0678 0.0929 -0.0087 -0.0104 0.1244 -0.0002 0.1003 0.1150 0.1089 -0.0069 -0.0264 0.0468 0.1284 0.1389 0.0774 0.1480 86.9 assembling Steel 5 reinforcement 64.9821 1.6610 -0.7335 0.0820 1.0915 -0.1616 -0.3539 1.1168 1.4406 1.1778 0.4393 0.3897 -0.2367 1.0419 1.4606 0.8113 1.6392 94.6 work 3 1 Excavation 3.8700 0.0599 0.0617 0.1019 -0.0047 0.0807 0.0597 0.0939 0.0076 -0.0034 0.0010 0.10430.1142 0.0254 0.1153 88.9 Border 2 sheeting 35.9491 -0.1677 -0.4216 0.1072 0.4442 0.8153 0.5894 0.7351 0.6177 0.7439 -0.1087 -0.2396 0.7310 1.1125 1.1190 -0.0879 1.1983 94.7 installation No. Table 10. Predicted Coefficients of Regression Equation Model for 21 work items in medium-class housing construction in Malang Journal of Science and Technology UTHM 87 12/21/2009 10:13:49 AM Journal of Science and Technology UTHM coordination (CC), rework (RW), tools (TL), experience (EXP), education (EDU), discipline (DSP), motivation (MTV), and skill (SKL) have a positive contribution to the productivity increase. On the contrary the variables: material distance (MD), weather (W), age (AGE) and health (HTH) give negative contribution. Variable ethnic does not have any significant effect on the productivity. The regression equations obtained for all work items have high coefficients of determination, which is more than 80%. This shows that in general the developed models are quite good to represent the relations between the variable productivity and the other affecting variables. The highest coefficient of determination is in the regrssion equation for border sheeting installation, which is 94.7%, while the lowest is in timber door and window installation, which is 80.2%. By inserting the data from each work item into the respective equation as concluded in Table 10, we can obtain the prediction value of the labor productivity in each work item. To compare the productivity to the one according to BOW 1921 and SNI 2001 it is necessary to equalize the effective working hours by changing the effective working hours used in SNI 2001 from 5 hours to 6 hours as in this research. The results can be seen in Table 11. Table 11 shows that compared to the conventional productivity of BOW 1921 and SNI 2001, there is a real difference with the productivity in 21 work items resulting from this research. The biggest difference is in the timber door and window assembling as much as 408% of SNI 2001, and in the timber formwork as much as 869% of BOW 1921, while the smallest one is in the productivity of steel reinforced work which is 8% of SNI 2001 and in concrete pouring 17% of BOW 1921. This research result has a similarity as well as a difference with the research of [11]. The similarity is on the internal factors: skill, motivation and discipline which are dominantly affecting the labor productivity. The difference is that the labor productivity model in this resaerch is more valid, shown by the smallest coefficient of determination of 80.2%, which in [11] was 68.47%. 5. CONCLUSION a. There are 16 out of 17 independent variables which affect the labor productivity in medium-class housing construction, either partially or simultaneously. The only variable which does not affect is the variable ethnic. b. The coefficients of the regression equation obtained for each work item show the contribution of the independent variables to the productivity, particularly the variables: skill, motivation, discipline, wage, communication and coordination, tools, rework and material supply have a strong effect. The variables: material distance, weather, site, experience, age and supervisor’s experience have a moderate effect, and the variables education and health have relatively weak effect. 88 chap 6.indd 88 12/21/2009 10:13:49 AM Journal of Science and Technology UTHM c. From the predicted model of productivity there is a quite significant difference between the conventional productivity (BOW 1921 and SNI 2001) and the actual one on site. The biggest differences are in the ceiling work and the door and window work, which is 840% to BOW 1921 and 428% to SNI 2001 respectively. The smallest differences are in the steel reinforced work and concrete pouring work, which is only 8% to SNI 2001 and 17% to BOW 1921 respectively as seen in Table 11. d. The models have a high precision and accuration (valid) as seen in Table 10. This can be seen in the value of R2, which is minimum 80.2% and maximum 94.7% as well as satisfying the validation of identical, independency and normally distribution tests. Table 11. Differences between the Productivity from the Research Result and the BOW 1921 & SNI 2001 NO Work Item 1 Soil excavation 2 Border sheeting installation 3 4 5 6 7 8 9 10 11 12 13 14 m3 (SNI 2001)* Productivity (Prediction) 3,87 ( 1 SL ) to BOW ‘21 189 To SNI 2001 30 259 200 231 38 3 ( 1 SL ) 0,035 0,084 0,116 m3 ( 1SL + 1/3UL ) ( 1SL + 1/3UL ) ( 1 SL ) 0,84 ( 1SL + 1/3UL ) 1,20 ( 1SL + 1/3UL ) 6,09 ( 1 SL ) 625 408 m3 16,4 60 65 296 8 kg ( 1 SL + 1 UL ) 5 ( 1 SL ) 12 ( 1 SL ) 48,47 869 304 m2 ( 1SL + 0,4UL ) ( 1 SL + 1,2 UL ) ( 1 SL + 1 UL ) 0,54 2 3,7 585 85 m3 ( 1SL+3UL ) ( 1 SL + 2,5 UL ) ( 1 SL + 2 UL ) 17 113 194 25 m3 1 0,55 1,166 ( 1SL+6UL ) ( 1 SL + 1 UL ) ( 1 SL + 1 UL ) 0,14 0,33 0,412 m3 ( 1SL + 1/3UL ) ( 1SL + 1/3UL ) ( 1 SL + 1 UL ) 0,042 0,10 0,269 540 169 m3 ( 1SL + 1/3UL ) 0,57 ( 1SL + 1/3UL ) 1,26 ( 1 SL ) 0,376 142 9,5 m3 ( 1SL+3UL ) ( 1 SL + 3,2 UL ) ( 1 SL + 2 UL ) 0,11 0,12 0,208 89 73 m3 ( 1 SL + 1 UL ) 10 ( 1 SL + 1 UL ) 15 ( 1 SL ) 27,668 176 84,5 m2 ( 1SL + 1,5UL ) ( 1 SL + 2,5 UL ) ( 1 SL + 2 UL ) 8,04 21,48 216 164 ( 1SL+3UL ) - - - Roof truss and purlin work Rafter and batten work Wall rendering 6,7 Molding plaster 16 Electrical & plumbing titik 17 Ceiling work 1,25 ( 1 SL + 1,34 UL ) ( 1SL + 1,5UL ) 15,5 ( 1 SL ) 2,4 5,07 ( 1 SL + 0,6 UL ) ( 1 SL + 1 UL ) 3,75 11,76 89 ( 1 SL + 0,6 UL ) - 111 840 241 m2 ( 1 SL + 1 UL ) 3,6 3,60 13,73 281 281 m2 ( 1 SL + 2 UL ) 0,6 ( 1 SL + 0,6 UL ) 1,20 ( 1 SL + 1 UL ) 3,10 416 158 m2 ( 1SL + 1/3UL ) ( 1SL + 1/3UL ) ( 1 SL ) Floor tile installation installation Compared Productivity (BOW) 1,34 ( 1 SL ) 35,95 Timber frame installation Door & window leaf Compared ( 1 SL + 1 UL ) 15 19 Result 12 Masonry foundation Roof tile installation % Difference Productivity ( 1 SL + 1 UL ) Steel reinforcement work Brick work % Difference Conventional 10 Door & window assembling Concrete pouring Analysis ( 1 SL + 1 UL ) Timber frame Form work Average BOW Revision m3 m2 m' 18 chap 6.indd 89 Unit Average Average ( 1 SL ) 12/21/2009 10:13:49 AM 9 10 11 12 13 14 Timber frame installation 0,14 0,33 0,412 m3 ( 1SL + 1/3UL ) ( 1SL + 1/3UL ) ( 1 SL + 1 UL ) 0,042 0,10 m3 ( 1SL + 1/3UL ) 0,57 ( 1SL + 1/3UL ) 1,26 m3 ( 1SL+3UL ) ( 1 SL + 3,2 UL ) ( 1 SL + 2 UL ) 0,11 0,12 m3 ( 1 SL + 1 UL ) 10 ( 1 SL + 1 UL ) 15 m2 ( 1SL + 1,5UL ) ( 1 SL + 2,5 UL ) ( 1 SL + 2 UL ) 8,04 21,48 Roof truss and purlin work Brick work Rafter and batten work Roof tile installation Wall rendering 6,7 194 25 0,269 540 169 ( 1 SL ) 0,376 142 9,5 0,208 89 73 ( 1 SL ) 27,668 176 84,5 216 164 - - - 111 840 241 Journal of Science and Technology UTHM 15 Molding plaster m2 m' 16 Electrical & plumbing titik - 17 Ceiling work m2 ( 1 SL + 1 UL ) 3,6 3,60 13,73 281 281 m2 ( 1 SL + 2 UL ) 0,6 ( 1 SL + 0,6 UL ) 1,20 ( 1 SL + 1 UL ) 3,10 416 158 m2 ( 1SL + 1/3UL ) ( 1SL + 1/3UL ) ( 1 SL ) 2,2 4,96 5,74 160 16 m2 ( 1SL ) 3,34 ( 1 SL ) 15,2 ( 1 SL ) 18,38 450 21 m2 ( 1SL ) ( 1 SL ) ( 1 SL ) 18 19 installation 20 21 1,25 Floor tile installation Door & window leaf Timber painting Wall painting ( 1SL+3UL ) - ( 1 SL + 1,34 UL ) ( 1SL + 1,5UL ) 15,5 ( 1 SL ) 2,4 5,07 ( 1 SL + 0,6 UL ) ( 1 SL + 1 UL ) 3,75 11,76 ( 1 SL + 0,6 UL ) ( 1 SL ) Note: SL Skilled Labor , UL: Unskilled Labor REFERENCES [1] Setyanto, E., Peter F. 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