UNIVERSITY OF NAIROBI SCHOOL OF THE BUILT ENVIRONMENT DEPERTMENT OF REAL ESTATE AND CONSTRUCTION MANAGMENT A STUDY ON THE EFFECTS OF DESIGN CHANGES ON THE CONTROL OF CONSTRUCTION PROJECTS IN KENYA; CASE STUDY OF NAIROBI COUNTY. SUBMITTED BY: AHMED ALBASHIR IBRAHIM REG NO. B66/0345/2009 A RESEARCH PROJECT SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENT FOR AWARD OF BACHELOR DEGREE OF QUANTITY SURVEYING. MAY 2013
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UNIVERSITY OF NAIROBI
SCHOOL OF THE BUILT ENVIRONMENT
DEPERTMENT OF REAL ESTATE AND CONSTRUCTION MANAGMENT
A STUDY ON THE EFFECTS OF DESIGN CHANGES ON THE CONTROL OF
CONSTRUCTION PROJECTS IN KENYA; CASE STUDY OF NAIROBI
COUNTY.
SUBMITTED BY:
AHMED ALBASHIR IBRAHIM
REG NO. B66/0345/2009
A RESEARCH PROJECT SUBMITTED IN PARTIAL FULFILMENT OF THE
REQUIREMENT FOR AWARD OF BACHELOR DEGREE OF QUANTITY
SURVEYING.
MAY 2013
i
DECLARATION
STUDENT
I Ahmed Albashir Ibrahim, declare that this is my original work and has not
been presented for any award in any organization of learning or examination
4.2 DEMOGRAPHIC INFORMATION ................................................................. 45
4.2.1 Information on line of business/Profession................................................. 45
4.2.2 Information on Duration of service on the respective line of profession ... 47
4.2.3 Information on the position of the respondents in the organization ........... 48
4.2.4 Information on the Professional Associations attached to the respondents...... 49
4.3 INFORMATION BASED ON THE STUDY OBJECTIVES ........................... 51
4.3.1 Information on whether the Projects involved have experienced changes inthe initial design......................................................................................................... 51
4.3.2 Information on how the respondents ranked the causes of changes in theinitial design. ............................................................................................................. 52
4.3.3 Information on how the respondents ranked the effects of design changes inconstruction projects in Kenya .................................................................................. 54
4.3.4 Information on the design changes and control of construction projects inKenya ……………………………………………………………………………..56
4.3.5 Information on the level at which the effects of the design changes affectthe control of construction project............................................................................. 56
4.3.6 Information on the possible methods of improving existing controltechniques on design changes in construction projects in Kenya.............................. 57
5.1 SUMMARY OF THE FINDINGS..................................................................... 61
5.1.1 Objective 1: Causes of Design changes. ..................................................... 61
5.1.2 Objective 2: Effects of design changes on the control of constructionprojects ……………………………………………………………………………..62
5.1.3 Objective 3: Project control tools that can be used to mitigate any effect ofdesign changes ........................................................................................................... 63
5 Lack of Definition of Architecture Elements 6.54% 53.05%6 Structure-Bid-Plans Modifications 6.39% 59.44%7 Lack of Architecture Dimensions 6.24% 65.68%8 Lack of Identification and Location of Architecture
Elements5.65% 71.32%
9 Finishing Materials that Require Samples 4.75% 76.08%10 Shaft Problems 4.46% 80.53%11 Design Defects in Sewerage and A.P. 4.16% 84.70%12 Architecture's Incorrect Cross Reference 3.12% 87.82%13 Design Changes by the Owner 3.12% 90.94%14 Electricity Design Defects 2.97% 93.91%15 Structure Plans Late Delivery 1.93% 95.84%16 Defects in A. C. Designs 1.49% 97.33%17 Problems with Electrical Equipment 0.89% 98.22%18 equipment’s Structure 0.59% 98.81%19 Problems with the Materials in the Market 0.45% 99.26%20 Symbology Conventions 0.45% 99.70%21 Gas Design Defects 0.30% 100.00%Source: Improving the design-construction interface by Luis and Daniel 1998.
The following are a summary of the common design changes causes as reviewed from a
study of Burati, et al (1992).
2.1.4.1 Change of Plans by Owner
In a study by Burati, et al (1992), Change of plans or scope of a project is by far the most
significant cause of changes in construction as stated in the literature. Normally this
source of changes results because of insufficient planning at the project definition
stage or simply because of the lack of involvement of the owner at the design stage.
This type of changes is normally costly especially if made later in the construction
process. An example of change of scope or change of plans is the increase in building
area, an increase or decrease in the number of floors. Early involvement of the owner in
the project objective definition and later in the design of the facility normally reduces
such changes to a minimum.
2.1.4.2 Owner Financial Difficulties
The owner of the facility may run into difficult financial situations that force him to make
changes in an attempt to reduce cost. The fact that many of the owners in this country
especially in large building construction projects are wealthy individuals who might not
have sound and reliable financial sources makes this risk a real one. Again proper
planning and review of the project cash flow is enough to eliminate this problem.
2.1.4.3 Owner Change of Schedule
The owner might change the schedule of the project, which might cause a change in the
design to be constructed so as to fit in the desired schedule. However, time has an
equivalent money value. This makes changes in the schedule as costly as change in scope
or materials. As the contract was signed the contractor has leveled his resources over the
time frame agreed upon with the owner. A change in the schedule means the contractor
will either provide additional resources in a shorter time or idle some sources that he
committed for certain activities. In both cases additional cost is incurred. Although there
are numerous causes of schedule change such as market conditions, user requirements, or
lack of funding, the owner must be certain that the cost of change of schedule is well
covered by the anticipated benefits.
2.1.4.4 Defined Project Objectives
This might be a sub-category of change of plans but specifically indicates that the
objectives of the project were not well defined. This will sure cause a change in the
design at a later stage of the project.
2.1.4.5 Substitution of Materials or Procedures
If the contract calls for certain materials or work procedures, then a change order is
required to substitute these materials or procedures. This is especially in the large
buildings, where material standardization is not common and some of the materials will
need to be imported, e.g. Aluminum cladding. The substitution of materials or the
procedure of construction may necessitate a change in design to accommodate the
substitution.
2.1.4.6 Conflict between Contract Documents
Quite often, different documents are drawn by different engineers or design personnel
during the design phase of the project. In spite of the close coordination between design
personnel or disciplines, discrepancies are sometimes found. Normally contracts include
guidelines as to which document governs in case of conflict. However the owner may
find out that the governing document representation or requirements are not the best and
may decide to change. Owner must expend sizable effort to review contract documents
for any possible contradictions before award of contract to avoid such changes. Phrases
that can be interpreted differently have to be rewritten if confusion is to be avoided. The
contractor will normally look for any phrase or note in the contract documents to
justifying the cheaper option.
2.1.4.7 Change in Design
The changes in design happen more in projects where construction starts before design is
finalized or in concurrent design and construction. The owner may opt for such a
philosophy if the project is schedule driven and time is the controlling element. Owners
normally object to any changes in design at this stage. However a new element of design
may not have been considered before or a clear design advantage that is assumed by the
change may favor going ahead with implementing this change. Change in design may
also take place when the design is reviewed by the consultant, who has a different
opinion than the designer, and he may wish to make changes. The owner or project
manager should be careful however of approving preferential changes.
2.1.4.8 The Scope of Work for the Contractor is defined
Here the change is not forced because of change of a mind by the owner as we noted
earlier, but rather because of lack of clarity in the documents about the scope of work.
This might happen for example when work is contracted to different contractors but the
boundaries are not made clear. It takes quite extensive efforts to draw the boundary lines
between different packages or phases of the same projects especially in large complex
projects where all systems are virtually interconnected. Clear demarcation on drawings
besides clarifying notes is a must to avoid such situations. In many instances, the owner
contracts a third party to do work that he thought was included but cannot prove it was.
2.1.4.9 Errors and Omissions in Design
It is impossible to create a 100% error free design. Quite often, among the many
documents of the project, one will find a note deleted, a detail mis-referenced or an
incomplete specification sheet. The contractor’s point of view is to escape the extra cost
and will look for ways to minimize cost. This is quite legitimate and justified. In this case
the owner will pay the extra cost (design change) or accept an inferior product or design.
A quality assurance program in the designer office should minimize this source of
changes.
2.1.4.10 Lack of Coordination
It is quite important in a multi-player environment like a construction project to keep
strong and continuous coordination. The owner should convey his new ideas and
concerns which form the basis for changes to the consultants in a timely manner. The
owner should avoid giving direct orders to the contractor without the involvement of the
party who is acting on his behalf. The consultant has to update the contractor of any
concern he might have with the scheduled work. If we keep in mind that changes have an
exponential relationship with time, we do not need to stress this point any further. Ways
to improve coordination include coordination meetings, progress reports, and conference
calls among others.
2.1.4.11 Technology Changes
Major construction projects and especially those which have technology items might face
this reason for change especially if the time between design and construction is long. The
presence of new technology in the market, a new desalination unit or a new erection
method might encourage the owner or the consultant to initiate this type of change.
2.1.4.12 Differing Site Conditions
This cause of changes happens most of the time on soil conditions in building
construction. The contractor may face rock instead of soft soil as the tender document
may have indicated. This will require extra effort for excavation and extra compensation
to the contractor.
2.1.4.13 Contractor Desire to Improve his Financial Conditions
Although no contractor wants to admit it, changes are looked at as a source of
additional work. The contractor may talk directly to the owner and convince him to do
certain changes only to give himself the additional benefit of change work. The
contractor may take any excuse to claim that certain parts of the work are not in his scope
and therefore request compensation for doing it.
2.1.4.14 Unavailability of Skills (Shortage of Skilled Labor)
Certain jobs may require certain expertise that is not available in the local market and for
that reason the owner or consultant may agree to modify the method or procedure of
construction. This type of change is more likely to happen in construction involving some
degree of technological complexity and not in normal building construction.
2.1.4.15 Unavailability of Equipment (Lack of Equipment)
Like the previous source of change the lack of a piece of equipment may force a change
to the plan. For example, lifting of some heavy structure may require crane capacity that
is not available in the country forcing the contractor to think of other lifting methods. The
danger in this comes from the fact that some designs are done outside the country by
companies not familiar with the resources available locally. Active participation of
the owner during design will minimize this source of changes.
2.1.4.16 Defective Workmanship
Defective workmanship of completed work may bring about demolition and re-work or
may bring about changes in some instances. Acceptance of defective workmanship due to
schedule may force a change in the facility to correct for it.
2.1.4.17 Safety Considerations
If some safety aspects were overlooked during the design phase, the owner or
consultant may initiate a change to install additional safety features in the facility. This
cannot be different from any other design oversight, except for the fact that safety is
usually un-compromised. The addition of specific safety controls such as a relief valve in
an industrial facility or an escape door in a building is typical of such changes.
2.1.4.18 New Government Regulations
Local authorities may have specific codes and regulations that must be adhered to.
Normally the designer insures that his design is in compliance with these codes.
However, new regulations may be issued between design and construction and may force
some changes to the original plan. Codes such as environmental or labor codes are
revised periodically and the contractor or facility owners are requested to comply.
2.1.5 Effects of Design Changes
There are numerous effects brought about by design changes and change order
in construction. In this section we examine some of these effects which are
commonly encountered.
The impacts of changes are not understood and rarely recognized, in terms of costs and
schedule. The work hours invested by the designers in the changes have been estimated
in a 40 to 50% of the total of a project (Koskela, 1992). In Latin American countries, it is
estimated that between 20 to 25% of the total construction period is lost as a product of
design deficiencies (Undurraga, 1996). On the other hand, for some Chilean construction
companies, the principal source of conflict in projects are the continuous changes in the
designs carried out by the owners, affecting quality and productivity and impacting the
schedule and the cost of the projects.
2.1.5.1 Decrease in Productivity
In a study by Thomas and Napolitan (1995) productivity values from three industrial
projects constructed between 1989 and 1992 were used in the analysis. The study
concluded that on average there was 30% loss of efficiency due to changes (25-50% was
the actual range). It is worth noting that Thomas and Napolitan concluded that changes
do not lead to productivity degradation or efficiency loss in themself. Instead, a
construction change causes other disruptive influences to be activated. In fact, Thomas
and Napolitan concluded that it is possible to perform changes without negatively
impacting labour efficiency. However, it is difficult to qualify this statement. Changes are
disruptive in nature and to think of eliminating some of these disruptions is impossible
before the change is introduced.
2.1.5.2 Delay in Completion Schedule
It is easy to document a schedule impact of a change after change work is done, because
all data is available regardless of its accuracy. However, it is difficult to predict impact of
change on schedule before making a change because of the many uncertainties related to
labour productivity, material availability or job interference. The cost of schedule
slippage becomes very high if the contract includes a penalty clause. Most projects are
planned using a critical path method, CPM, (CII publication 6-10, 1990). This method of
scheduling shows the activities included and their dependencies. CPM provides the basis
against which impact of changes on schedule can be evaluated. Floats both total and free
play an important role in schedule impact evaluation for they represent the flexibility
available to handle the unforeseen conditions such as changes.
The magnitude of schedule slippage due to changes is reported by Zeitoun and
Oberlender (1993) as 9% of the original schedule on average for 71 fixed price projects
studied.
2.1.5.3 Dispute between Owner and Contractor
Changes and change orders are among the most common reason leading to claims and
disputes. All other work is agreed upon in the contract. However changes must go
through evaluation, estimation and negotiation leading to stress and strains in the relation
between parties. If these disputes are not settled peacefully through direct
negotiations and arbitration they end up in court and legal procedures may suspend the
whole project (James, 1984).
2.1.5.4 Decrease in Quality
Sometimes changes lead to a lower level of workmanship. As changes alter the original
plan in certain items or areas, they might create a mismatch with other items or areas
affecting the overall quality of the work. As discussed above, the low morale of the crew
after many changes are made is also expected to affect the quality of their
performance (Kevin, 1983).
2.1.5.5 Increase in Project Cost
To make a change and process takes time. This usually results in placing a hold on the
work and waiting for new instructions to come. In addition, equipment, tools and
materials may not be the same after the change is introduced. To procure or rent new
material, tools and equipment will cause delay and cost of resources may be substantial.
Furthermore, if delays are prolonged demobilization/remobilization may become quite
costly.
2.1.5.6 Additional Money for Contractor
No matter how much was said about the negative effects of change orders, there is often
additional money gained by the contractor for executing additional scope
(Krone,1991). The accuracy of this statement depends on the awareness of contractors
and owners of direct and indirect impacts of changes and on the willingness to accept this
fact in change order pricing.
2.1.5.7 Delay of Material and Tools
Change orders bring about problems with materials and tools required to carry out a
certain activity. Consider for example an order to change the type of doors of a building
at a time after the order for doors was issued to the vendor. The new type of doors may
not be available from the vendor and may require extra time to order or fabricate. This
creates delay for materials which in turn holds up work for finishing subsequent work
(Algimantas, 1998). The delay of tools happens for example when a certain erection
procedure has changed requiring a larger crane that is not readily available. The cost of
such a delay can be quite costly.
2.1.5.8 Work on Hold
Change in a certain work package can put the work on other activities on hold. This
happens when activities are interdependent. This action may freeze a certain craft crew or
shift the schedule of its schedule. Speedy and quick change order procedures are very
vital in order to minimize this effect (Gilbreath, 1992).
2.1.5.9 Increase in Overhead Expenses
Normally change orders require processing procedures, paper work and reviews before
they even proceed. They may require use of funds that otherwise will be used for other
activities. These minor expenses are normally not charged to the change order account as
they are difficult to define and separate from the different accounts (Cox, 1997). The
charge normally goes on the contractor’s overhead account.
2.1.5.10 Delay in Payment
If payments due to the contractor are made against a certain milestone then there is a
possibility of delay in payment as a result of a change that delays the achievement of that
milestone.
2.1.5.11 Demolition and Re-work
Quite often, changes that occur after construction of the project cause some parts of the
work done to be demolished and done again. This is the worst phase to think of changes
and the cost of changes is the highest on the project time curve. JBC condition of contract
for building works (1999) state that no instructions for variations shall be issued after the
practical completion certificate is issued without the consent of the Contractor.
2.1.6 Control Tools used to handle Design Changes
In this section we will review the common control procedures used to minimize the
effects of change orders. These include measures taken prior to the start of construction
and before generation of change orders and measures taken to minimize impact of change
orders after they have been generated.
2.1.6.1 Clarity of Change Order Procedures
Every project team must ask these questions before the kickoff of the project in relation
to design changes:
a) Are the procedures to handle changes clear to all parties?
b) Are the forms and instructions to complete them available?
c) Are the people responsible for approving, negotiating, and reviewing changes
identified?
The clarity of these procedures at the beginning of the job will save a lot of time and
effort. (Kuprenas, 1998).
2.1.6.2 Quick Approval
The time between recognizing the need to make a change and actually doing the change
can be days or months. The longer the period between recognition and implementation,
the more costly the change is. Because of the dynamics of construction projects, work
impacted by changes increases as the project progresses to a more detailed phase
(Cooper, 1995). This control is quite important in large organizations or large projects
and a multi- player environment.
2.1.6.3 Ability to Negotiate Changes
There are certain skills required to be able to negotiate change orders. Knowledge of
contract terms, project details, technical background in the field, and negotiation skills
are required to come to a successful agreement on change orders (Emory, 1995). Lack of
any of these skills may complicate the negotiation and lead to disputes, delays or making
the wrong decision.
2.1.6.4 Approval in Writing
Changes should not be made without approval in writing. It is difficult to prove the right
for compensation if there is no authorization in writing from the owner (Rowland, 1981).
Even the JBC condition of contractor for building works (1999) insist that all instructions
given by the architect and the owner to the contractor, which will lead to a variation or a
change, be in writing. In the hectic environment of construction many verbal agreement
can be forgotten leaving the contractor disarmed in the battle to get compensation for a
change.
2.1.6.5 Change Order Scope
Like the original scope of a project, the scope for a change must be clearly defined.
Affected drawings must be reviewed to insure the extent of construction or demolition
and to see the effect of this change on other parts of the facility. This gets critical when
working in a renovation project where there is a constant interface with existing structure
(Robert, 1990).
2.1.6.6 Pricing of Indirect Effects
We have seen in our literature review that changes have direct as well as indirect effects
on projects. Often indirect effects are not accounted for. In simple projects this might not
be a problem. However indirect effects can be substantial in more complex projects.
These effects include effects on labor productivity, additional bonding and
insurance, extra overhead expenses, shift of schedule to a less favorable period,
etc. Pricing of change orders must consider these factors to come up with fair
compensation (Saudi, 1995).
2.1.6.7 Justification of Changes
Any change request must be carefully examined to insure there is enough
justification. Knowing the problems associated with construction changes, the authority
that approve change must insure a high benefit to cost ratio to precede with the change
(Rowland, 1981). An extra effort must be exerted to determine the extent of the effect of
a change on scope, cost, material, finance etc. before approval.
2.1.6.8 Review of Contract Documents
Owners and contractors must review contract terms and documents prior to bidding
or award. In many instances, specific teams are formed to carry out this review. Improper
use of change potential in the document can cost a lot. Special attention must be given to
gray areas where different interpretation can arise (Bruce, 1999). Clarifications shall be
made as early as possible to the particular vague part of documents. In many cases, it was
seen that unanswered question is carried over from the conceptual development of the
project all the way to construction phase.
2.1.6.9 Freezing Design
Many owners consider this measure after feeling that the design has developed to a
satisfactory level. This is quite effective in a large multi-departmental owner
organization. (Stephen, 1992) In such a case each department may continue to request
modification to the scope. By using this scope control procedure, the owner is
committing himself to a comprehensive review at early stages of the project.
2.1.6.10 Team Effort
Many researchers have concluded that team effort minimizes impact of changes.
Encouraging teamwork is considered an effective control in change management. This
approach requires that all parties (owner, contractor ,and consultant) work together to
identify and implement project changes and openly share information on pricing and
implementing of changes (John, 1991).
2.1.6.11 Use of WBS
As discussed in the literature review, an effective means of tracking the cost of change
orders is the use of Work Breakdown Structure (WBS). This technique allows the project
management to see the effects of a change happening in a certain work package on other
work packages represented in the WBS tree (Weston, 1991).
2.2 CONCLUSIONS
A lot has been written on the field of design changes in the construction industry with
many different writers giving different perspectives to it. Schools of thought are
developing with some conflicting with each other, while some just modify existing ones
especially on the causes and effects of design changes in the construction industry. The
above review attempted to highlight the common grounds between the various scholars
on the focus area of the study.
Control of construction projects on the other hand, is a fairly standard activity and
consists of laid down principles which different people attempt to follow. Hence, there is
very little variation of thought among different writers on the field. These principles have
been tried over time and their effectiveness in controlling design changes was reviewed.
The identification of the causes of design changes, its effect on the control of
construction projects and the different control tools used to mitigate its effect was as a
result of the synthesis of the three areas of study.
CHAPTER THREE
RESEARCH METHODOLOGY
3.0 INTRODUCTION
This chapter will focus on giving details on how the research was done. It focuses on the
determination of research design, the type and sources of data, research population,
sampling design, data collection, data collection instruments, data analysis, adherence to
research ethics and research reporting. The chapter will also address the difficulties that
were faced by the researcher during the study.
3.1 RESEARCH DESIGN
Research design is a strategy used in collecting and analysis of data in order to answer
research questions and test research hypothesis. The research design that was used in this
study is descriptive design. According to Kothari (2004), descriptive research design is
the arrangement of conditions for collection and analysis of data in a manner that aims to
combine relevance to the research purpose with economy in procedure. In fact, research
design is the conceptual structure within which research was conducted; it constituted the
blueprint for the collection, measurement and analysis of data. As such, the design
included an outline of what the researcher did from writing hypothesis and its operational
implications to the final analysis of data.
3.2 STUDY POPULATION AND DESCRIPTION OF THE STUDY AREA.
Study population is defined as the aggregate of all study unit, they have a potential for
providing relevant data for the study. A particular population has some characteristics
that differentiate it from other population. The research targeted the Nairobi County. The
study area was preferred because most construction activities involving consultants and
contractors take place in Nairobi as opposed to any other part of the country. Besides,
most of the consultants in the study were concentrated in the area. Sources from the board
of registration of architects and quality surveyors (BORAQS) demonstrated that about
75% of the total population of consultants is based in Nairobi. The study area was also
chosen because of its proximity to the researcher, and also due to constrain of time and
money. It is however assured that the findings from the research gave an overview of the
entire construction industry all over the country.
3.3 TARGET POPULATION
Mugenda (1999) refers to population as an entire group of individuals, events or objects
having the common observable characteristics to which the research wants to generalize
the result of the study. The target population under study was professional practicing
firms in the construction industry in Kenya. They include contractors and consulting
quantity surveying, architectural and engineering firms together with the developers who
were involved in the projects. The accessible population includes developers/clients,
contractors and the consultant team of projects approved by Nairobi city council (NCC)
for the year 2011 and 2012. According to the minutes of proceedings of approved
building plans from the Nairobi city Council, department of development control, 8125
building plans were approved for development in the year 2011 and 2012. The study,
however, considered large construction projects with an estimated cost of over 100
million, this, according to the minutes, resulted to a population of 488 projects. Some of
the developers, contractors and consultants had more than one project. The target
population of developers, Architect, Engineers and the contractor were identified as
below tabulated;
Table 3.1 Target PopulationFirms Target Population (n) Percentage
Developers 162 30
Consultant 112 21
Engineering 113 21
Contractors 148 28
Total 535 100Source: NCC minutes of proceedings from 2011 to 2012
3.4 SAMPLING DESIGN
Due to the big size of the research population there was a need to do sampling. It was
impractical to carry out a study in an organization with a population of 535 due to time
and financial constraints. Sampling allowed the researcher to collect data from a
representative size of the target population.
3.4.1 Sampling Method
The sampling method that was used in the study is probability sampling. This is the
appropriate method of sampling because it involves random sampling which gives all the
members of the research population equal chances of being represented in the study. This
method is not biased and therefore produces a sample size that is representative to all the
firms of the study population.
3.4.2 Sampling Technique
Stratified random sampling technique was used in the study. The technique was used
because it ensures that all the firms in the target population were represented. It will be
possible to find a representative sample size for the study using this technique because
the study area on which the study was carried out has four categories that will be
classified as strata during the study.
3.4.3 Sampling Procedure
The sampling frame for this study was the developers, contractors and consultants in
Nairobi County. After identifying the target population, the investigator selected a sample
out of the target population. The sample size will be determined using the following
formula for descriptive study:
n = z2pqN
e2(N-1) + z2pq
Source: Chara and Nachamias (1996)
Where;
n= Sample required from the population
N=Population size (535)
z= Standard normal deviate corresponding to 95% level of confidence= 1.96
p=Sample population estimated to have characteristic being measured.
q= (1-p)
e=Margin of error set at 5 %
Substituted:
The sample size was thus arrived at as follows;
n = (1.96)2 x 0.95 x 0.05 x 535
(0.05)2 x (535-1) + (1.96)2 x 0.95 x 0.05
Sample size (n) = 64.33 approximately 65
Sample size percentage = 65 x 100
535
= 12.15%
Sample size = Sample Size Percentage x Target Population
Developers = 12.15% x 162
= 20
Architects = 12.15% x 112
= 14
Engineers = 12.15% x 113
= 14
Contractors = 12.15% x 148
= 17
Table 3.2 Sample SizeFirms Target
Population (n)Sample Size
Developers 162 20
Lead consultant (Arch. Or QS,PM) 112 14
Engineering 113 14
Contractors 148 17
Total 535 65
Source: Author (2013)3.5 DATA COLLECTION
The type of data that was used for the study is primary. This is the first hand data that
was collected directly from the field. The study primarily used first hand data collected
directly from the respondents. Secondary data was used as reference material sourced
from past research studies, textbooks, journals and articles.
3.5.1 Method of Data Collection
Questionnaire method will be used in data collection for the research study. The size and
nature of the research population demands that a fast and confidential method of data
collection be used in the study. Non-verbal means of questioning will be used in order to
enhance the confidentiality of the data collected.
3.5.2 Instruments of Data Collection
The instrument of data collection that was used in the study is questionnaires. These are
written forms comprising of a set of questions that will be used to gather the data required
from a sample population. Each item in the questionnaire is developed to address the
research objectives. Unstructured and structured questions were used in the research
study.
3.5.3 Data Collection Procedure
The questionnaire contains a set of closed and open ended questions. Open ended
questions will give the respondents complete freedom of response which allows them to
respond in their own will and express what they consider important. The questionnaires
will be prepared and delivered to the respondents by the researcher. The researcher will
agree on the period during which the questionnaires will be filled and dropped back to the
researcher.
3.6 DATA ANALYSIS
The data collections instruments was collected and verified if they are dully filled by the
respondents. Questionnaires that did not have 80% of the questions answered were not
included in the analysis. The collected data was classified, coded, corrected, analyzed and
then interpreted. Both qualitative and quantitative methods were used for the analysis.
3.7 DATA PRESENTATION AND ANALYSIS
The data obtained by the use of the questionnaires was interpreted in relation to the
information obtained from the literature review with regard to the causes, effects of
design changes on the control of construction projects and control tools used to mitigate
the effects. This was then summarised in the form of tables, graphs and pie charts
depending on the type of data and the suitability of the mode of presentation for the same.
The data was analysed by considering each of the questions contained in the
questionnaire and the frequencies noted for the responses to each of them. These were in
the form of percentage distributions. From these responses, the researcher gauged the
effects of design changes on the control of construction projects in Kenya.
In doing this analysis and presentation, the researcher made extensive use of the MS
Excel office application.
CHAPTER FOUR
RESEARCH FINDINGS
4.0 INTRODUCTION
This section presents the research findings beginning with response rate and demographic
information of the respondents. The other sub-sections were presented based on the study
objectives. These were to establish the effects of design changes on the control of
construction projects in Kenya; case study of Nairobi
4.1 RESPONSE RATE
The table below shows the response rate
Table 4.1: Response Rate
Firms Number of respondents Non-response
Frequency % Frequency %
Developers 20 31% 0 0%
Lead
consultants(Arch,QS,PM)
10 15% 4 7%
Engineering 14 21% 0 0%
Contractors 15 23% 2 3%
Total 59 90% 6 10%
Source: Fieldwork 2013
The table shows that after the data collection 59 questionnaires were filled and returned
for analysis giving a response rate of 90% and 10% non-response rate. These were
distributed as 20 (31%) from Developers, 10 (15%) for Lead consultants, 14 (21%) from
Engineering and 15 (23%) from Contractors. This commendable response rate was
realized as a result of the researcher’s plea to the respondents on maximizing on data
collection and making follow ups to ensure that the data collection process was carried
out as planned. Most of the respondents were people of significance and vested interest in
the study area and this ensured credibility of the data collected.
Figure 4.1 Response rate
Source: Fieldwork 2013
4.2 DEMOGRAPHIC INFORMATION
4.2.1 Information on line of business/Profession
The first item on the demographic information sought to group respondents according to
their line of profession/business the following Table 4.2 indicates the distribution of
respondents according to their line of business.
Table 4.2 Line of business/profession
Line of Business Frequency Percentage%
Architect 4 7%
Quantity surveyor 3 5%
Engineer 14 24%
Contractor 15 25%
Developers 20 34%
Project Managers 3 5%
Total 59 100%
Source: Fieldwork 2013
The table shows that there were 4 (7%) Architects, 3 (5%) Quantity surveyors, 14 (24%)