Identification and analysis of factors affecting labour productivity in Iraq

Productivity is a very important element in the estimation process in construction management. The objective of this research is to identify and analyze the factors which affect labor productivity in construction projects. In this research, 42 effective factors were collected from site survey, interview with engineers and experts, and previous research in the Arab world. These factors are grouped into Nine categories "Workforce, Leadership, Motivation, Supervisors, Safety, Project, Time, Material, and External". A survey questionnaire of 70 respondents was distributed among different experts. A statistical analysis was done using SPSS and EXCEL packages. The Relative Importance Index was used to find out the most significant factors affecting the labor productivity in construction sites. The results accomplished from the survey revealed that the major factors negatively affect the labor productivity (ranked from the worst factor with Relative Importance Index values, respectively) namely, Availability Material (88.571%), Climate status "Weather" (88%), Religious occasions (86.29%), Number of working groups (86%), Ganger experience (85.714%), Workforce surveillance (84.857%), Ganger Age (84%), working at height (82%), Drawings and specifications alteration during execution (81.69%), and Sequence of floor (80.571%). Based upon these findings, this can help the construction professionals to improve the productivity and project performance in Iraq.


Introduction
The productivity of labor plays a major role in the success of any construction project. Therefore, the construction industry plays an important role in the economy of any developing country. The productivity is associated with the performance of the workers and this is considered most the important factor that has a significant impact on the growth of the construction industry [1]. Thus, improving productivity in construction projects and construction contributes significantly to gross domestic product of any country [1]. However, the productivity may be affected by many factors and variables unexpected difficulties. Such variables include factors related to manpower, materials, tools, equipment, construction methods, political factors, finance and other internal and external factors. In order to improve and increase the productivity of labor, the factors affecting productivity, must be reduced through study, identifying and analyzing the factors that have the highest impact on labor productivity. According to [2], the improved productivity is a major concern for any project aiming at success and profit or optimal use of resources, or as an effective and efficient conversion of resources into marketable products and identify business profitability. Currently, the construction industry in Iraq, suffers significantly from delay in the completion of projects, as well as excessive and increasing costs, which are indicators of the existence of problems in productivity. So this paper aims to identify the most important factors that affect the productivity of labor in construction projects in Iraq.

Research objectives
This study aims to: 1. Identify factors influencing the productivity of work in construction projects in Iraq 2. Analyze and rank the factors influencing the productivity of labor through the Relative Importance Index in the Iraqi construction projects, these factors can be used by the private and public sectors to improve and increase productivity in projects and control the quality of work performed. achieved by workers". Whereas the researchers Handa and Abdulla [5] defined productivity as "the rate output of goods and / or services on the input of the basic resources, for example, of workers, capital, technology, materials and energy". The researcher Finke's [6] definition of productivity is "the amount of work produced by one worker in an hour and the equipment used during the hour, or the crew during the same hours". The American Society of Engineers defines productivity costs as a "relative measure of the efficiency of the labor, whether it was good or bad this efficiency, compared with the established rules or standards required" [7]. The researchers Horner and Duff [8], define productivity as the "quantity produced per unit with input". Relying on the previous definitions, the present paper defines productivity, as "a method to measure the efficiency of work through the exploitation of resources available at the workplace.". From the above definitions, it is concluded that the productivity is generally defined as the ratio of outputs:

Factors Influencing labor productivity
Over the years, the factors that affect the productivity of labor have been the subject of investigation by many researchers. The importance of these factors varies from one country to another, and from one project to another. Table (1) illustrates the most important results of some researchers conducted in some countries. Table 1. The most influential factors, labor productivity

Researcher /year The most influential factors
Many researchers in engineering project management in most developed countries have tried to classify the factors affecting labor productivity in construction projects in major global groups. Through the adoption of many techniques and methods to classify the factors affecting, however, the researcher noted that there is no convergence of views and classifications in different research, as shown in Table (3).

Design of the questionnaire
The questionnaire included two parts: the first section includes general information about the participant. Also, it includes specialization, current work, years of experience, academic qualifications and the Guild degree; and answers are made by ticking the appropriate choice. The second section includes nine tables, which represent the nine groups of factors influencing the productivity of labor and the scale dish Likert quintet is used in the design of the questionnaire [31]. So the scale extends from (2 very low) to (5 very high). To confirm the consolidated, the results of the questionnaire, a second assessment has been conducted after reviewing and auditing to ensure its effectiveness and suitability for the construction projects in Iraq. The original questionnaire consists of 42 factors affecting labor productivity in construction projects in Iraq. Before distributing the questionnaire, a pilot test (pilot study) has been conducted to ensure that the questionnaire was designed gradually and appropriately simpler. The questions in the questionnaire are forwarded to six of arbitrators (degree expert engineer) as referees for the purpose of benefiting from their expertise in making the necessary adjustments to delete and add to reach the final version of the questionnaire.

Sample size
The sample of target in the search, the respondents are engineers who work as: operational director, project manager, project coordinator, construction manager, site manager, site engineer, superintendent, estimator, supervisor, etc. They work at contractor companies in Iraq both private and government. To get a statistically representative sample of the target, using equations (1),(2) which have been used by many researchers, including Hogg & Tannis, [32].
The m=Sample size of the population is not limited,

N= Sample size from a limited population
To find the value of (m), equation (2) is used as below: Whereas: (Z) = value shows the level of confidence (for example, 2.92, 1.575 and 2.245 represent the values of the confidence levels at 99%, 95% and 90% respectively), (P) = degree of contrast between the target sample elements (0.5) (E) = choice for point of maximum error.
Using a confidence level of 95% and the level of significance at 5% when the sample size is not specified, the estimated value (m) = clear application of the equation No. (1) As Follows:

Data collection
The target sample of this research is engineers working in the public and private sectors and in various administrative fields. Such as, project manager, supervision engineer, design engineer, road engineer and others. Among the 100 engineers (N=100), the required sample size to succeed in work of the total target sample can be calculated by applying the following equation (2) as follows: To ensure obtaining the required sample size (79 samples), (100 questionnaire) forms were handed out.
(79 Questionnaire) forms were filed in time and the number represents the ratio (79%). (9 questionnaire) forms were excluded due to incompleteness, bringing the total questionnaires after the revision, which were used for the analysis to (70 questionnaire), which constitute the ratio (70%). To analyze the data, using the (Relative Importance Index, RII) according to the following equation (3), [20,17,23]: Where: n1, n2, n3, n4 and n5 = the number of respondents who selected: n1= number of respondents who selected little effect.
n2= number of respondents who selected some effect.
n3= number of respondents who selected average effect.
n4= number of respondents who selected high effect.
n5=number of respondents who selected very high effect.
In contrast, these five expressions are defined by the equal intervals, as the following,

Measuring the consistency of the questionnaire
Stability is defined as the stability of the scale and lack of contradiction with itself, meaning that the measure would be re-applied to the same sample over a period of time and it will give the same results, the value of consistency between the two values will be zero or one, where the closer the value of one indicates the high stability of the questionnaire and vice versa. In order to measure the stability of the questionnaire, this study uses the stability coefficient (Cronbach's alpha) for equation (4) to ensure the stability of the search tool, and use equation (3) to come up with a valid value (Cronbach's Alpha), where the normal range of Cronbach's coefficient (Alpha) value is between (0.0) and (1.0). The closer the Alpha is to (1) the greater the internal consistency of data [33].

…..….(4)
Whereas: K: number of items in a group. s2i: the variance associated with the item (I). s2 t: the variance associated with the sum of all (k) item scores.…… (3) Table (4) demonstrates the values of trust and credibility for each factor in the questionnaire according to Cronbach's Alpha. Chronbach's shows that the Alpha values are in the range of (0.916 to 0.981). This is a high-scale (Excellent), and, therefore, it ensures the reliability and validity of each group in the questionnaire.

Results and discussion
In this study, 42 factors that negatively affect the labor productivity in the construction of buildings in Iraq have been identified and ranked according to the Relative Importance Index. These factors have been categorized into nine groups.
To find the results of this research, the following software has been used: 1. (SPSS) version 22 is employed to find the Relative Importance Index and Chronbach's Alpha of the impact strength (1 to 5) for each factor individually according to participants, replies to the questionnaire, and to find frequencies that are used in the calculation of importance coefficient.
2. Excel program (MS Excel 2015) for the application of the formula for the calculation importance coefficient

Workforce group
The Relative Importance Index and ranks of the seven factors are classified under the "Workforce Group'' as shown in Table (5).   (5) illustrates that the surveyed participants ranked ''Number of working groups'' as the most important factor that influence labor productivity in this group, with a RII of 86%. This top ranked factors influence is further ranked as the fourth in its effect among all factors explored. In contrast, the factor "Misunderstanding between Workforce'' is the least important factor that influences labor productivity in this group, with a RII of 60.3%. This group scored the fourth rank.

Leadership group
The Relative Importance Index and ranks of the three factors are classified under the "Leadership Group'' as shown in Table (6).   (6) shows that the surveyed participants ranked ''Lack of Workforce surveillance'' as the most important factor that influences labor productivity in this group, with a RII of 84.86%. This top ranked factors influence is further ranked as the sixth in its effect among all factors explored, contrariwise, the factor "Lack of periodic meeting with Workforce'' is the least important factor that influence labor productivity in this group, with a RII of 55.14%. This group scored the seventh rank.

Motivation group
The Relative Importance Index and ranks of the fourth factors are classified under the "Motivation Group'' as shown in Table (7).   (7) illustrates that the surveyed participants ranked "Payment delay'' as the most important factor influencing labor productivity in this group, with a RII of 78%. This top ranked factors influence is further ranked as (Twelft) in its effect among all factors explored, contrastively, the factor "Lack of training sessions'' as the least important factor that influence labor productivity in this group, with a RII of 54%. This group scored the eighth rank.

Supervisors group
The Relative Importance Index and ranks of the fourth factors are classified under the "Supervisors Group'' as shown in Table (8). Table (8) illustrates that the surveyed participants ranked "drawings and specifications alteration during execution'' as the most important factor that influence labor productivity in this group, with a RII of 80.29%. This top ranked factors influence is further ranked as the (Nine) in its effect among all factors explored. Contrariwise, the factor "Inspection delay'' is the least important factor that influences labor productivity in this group, with a RII of 72%. This group scored the second rank.

Safety group
The Relative Importance Index and ranks of the fourth factors are classified under the "Safety Group'' as shown in Table (9).   (9) illustrates that the surveyed participants ranked "Working at high place'' as the most important factor that influence labor productivity in this group, with a RII of 82%. This top ranked factors influence is further ranked as (The eighth) in its effect among all factors explored, In contrast, the factor "violation of safety precautions'' is the least important factor influence labor productivity in this group, with a RII of 57.71%. This group scored the ninth ranks.

Project group
The Relative Importance Index and ranks of the eight factors are classified under the "Project Group'' as shown in Table (10).  Table (10) illustrates that the surveyed participants ranked "sequence of floor'' as the most important factor that influence labor productivity in this group, with a RII of 80%. This top ranked factors influence is further ranked (tenth) in its effect among all factors explored. Contrastively, the factor "Type of activities in the project'' is the least important factor that influences labor productivity in this group, with a RII of 54%. This group scored the sixth rank.

Time group
The Relative Importance Index and ranks of the eight factors are classified under the "Time Group'' as shown in Table (11).   (11) illustrates that the surveyed participants ranked "Misuse of time schedule'' as the most important factor that influences labor productivity in this group, with a RII of 75.14%. This top ranked factors influence is further ranked (fourteenth) in its effect among all factors explored, while, the factor "Work overtime'' as the least important factor influencing labor productivity in this group, with a RII of 66%. This group scored the fifth rank.

Material / Equipment group
The Relative Importance Index and ranks of the eight factors classified under the "Material and Equipment Group'' are shown in Table (12).   (12) illustrates that the surveyed participants ranked "availability of material'' as the most important factor that influence labor productivity in this group, with a RII of 88.6%. This top ranked factors influence is further ranked as (the first) in its effect among all factors explored. In contrast, the factor "Inefficiency of equipment'' is the least important factor influencing labor productivity in this group, with a RII of 62%. This group scored the fifth rank.

External group
The Relative Importance Index and ranks of the eight factors are classified under the "External Group'' as shown in Table (13).   (13) illustrates that the surveyed participants ranked "Weather changes'' as the most important factor influencing labor productivity in this group, with a RII of 88%. This top ranked factor's influence is further ranked as (second) in its effect among all factors explored, while, the factor "Impact of neighboring buildings'' as the least important factor influence labor productivity in this group, with a RII of 73.71%. This group scored the first rank.

The ten Most influential factors on labor productivity (using the fishbone technique)
A Fishbone diagram, also called a cause and effect diagram or Ishikawa diagram, is a visualization tool for categorizing the potential causes of a problem in order to identify its root causes.
Table (14) and Figure (1) show the results of the most influential factor in productivity through the results of the survey. It is found that the highest factor affecting is the "availability of materials in the project" and the value of the Relative Importance of this Index is (88.571%), while the factor that occupies the tenth position in the ranking is the floor of the sequence and the value of the Relative Importance Index (80.571%).

Overall ranking factors
Relative Importance Index and ranking of all investigated 42 factors that affect labor productivity in the construction sector in Iraq are listed in Table ( 15). The analysis clarifies the followings: (1) there are 10 factors with importance index higher than 80%, (2) the minimum importance index is 54%. These indicate that the identified factors are highly relevant to the problem of labor productivity in public and private construction sectors in Iraq. Table (15) shows that the top ten important factors affecting labor productivity in public and private construction projects in Iraq among engineers who work in the construction sector. They are ordered as follows: (1) Availability of Material, (