Chapter 2: Literature Review

2.1 Categories of building projects

Building construction projects can be divided in to three parts.

1. High rise building projects

2. Medium scale building projects

3. Small scale building construction projects

High-rise buildings are buildings, which have 10 or more than 10 stories. Mainly high
rise buildings are used for office complexes and apartment complexes. These are
owned by private companies or the govemment. Most of these buildings are
constructed by private construction companies. Since the cost involvements of these
constructions are high, these buildings can be constructed only by the construction
companies, which have ICTAD grades M1 or M2. The private consultancy
companies do the Consultancy pati of these buildings. High-rise building projects are
normally constructed at urban areas. Recently most of these building projects were
started in Colombo and suburbs in Sri Lanka to facilitate the housing demand of
urban population.

Medium scale buildings are those, which have 2 to 10 stories. These buildings also
used as office complexes, shopping complexes and apartment complexes. These are
owned by individuals, private companies or the govemment. Most of these buildings
are constructed by private construction companies with the consultancy of private
consultation companies. Due to the cost involvement, construction companies which
having ICTAD grades Ml, M2 or M 3 can engage in construction ofthesc buildings.

11
Small-scale construction projects are mainly consists of house construction projects.
Houses are considered as individual dwelling units. Normally houses consist of single
or two-storied buildings. Most of the occasions in house construction projects, the
involvement of the consultants is limited to prepare of designs. Usage of proper
project management methods is also minimal in these projects.

In this research, our focus is mainly on medium scale building construction projects.
Since these buildings are constructed all over the Sri Lanka, identification of causes
of project delays and their effects can be of great help for the professionals working
in those projects.

2.2 Types of Project Delays

Delays can be due to the fault of consultant, contractor or client. They can be
categorized in to three types (Williams, 2003).

o Excusable compensable delays

These delays are occurring due to the fault of clients. Therefore, contractors can claim
for damages and extension of time.

o Excusable non compensable delays

These are occurring due to other causes excluding the faults of clients and
contractors. Therefore, contractor can claim for extension of time. However,
contractor cannot claim for the damages. At the same time, clients cannot claim for
liquidation damages as well.

• Non excusable non compensable delays

These delays occmTed due to contractors' faults. Therefore, the contractor cannot
claim extension of time whereas, clients can claim for the liquidation damages of

such delays.

12
 2.3 Studies on Causes of Project delays

There are many studies carried out in all over the world to identify the causes of the
project delays. However, specific studies to identify the causes and effects of project
delays were limited.

Sambasivan and Soon (2007) conducted a study to identify the causes and effects of
the project delays in Malaysian construction industry. They have initially identified
28 causes for delays of construction projects. They have divided these causes in to
eight categories as follows,

1. Client related causes

1. Finance and payments of completed work

11. Owner Interference
111. Slow decision making
1v. Unrealistic contract duration and requirements imposed

2. Contractor related causes

1. Subcontractors
11. Site management
u1. Construction methods
IV. Improper planning
v. Mistakes during construction stage
v1. Inadequate contractor experience

3. Consultant related causes

1. Contract management
11. Preparation and approval of drawings
111. Quality assurance/control
IV. Waiting time for approval of tests and inspection

13

...
 4. Material related causes

1. Quality of material
11. Shortage in material

5. Labor and equipment category causes

1. Labor supply
11. Labor productivity
111. Equipment availability and failure

6. Contract related causes

1. Change orders
11. Mistakes and discrepancies in contract document

7. Contract relationship related causes

1. Major disputes and negotiations

11. Inappropriate overall organizational structure linking to the project
111. Lack of communication between the parties

8. Extemal causes

1. Weather condition
11. Regulatory changes
111. Problem with neighbors
IV. Unforeseen site condition

Accordingly, major causes of project delays in Malaysian construction industry are

identified as follows (Sambasivan & Soon, 2006).

14

I.-
 1. Contractor's improper planning
2. Contractor's poor site management
3. Inadequate contractor experience
4. Inadequate client's finance and payments for completed work
5. Problems with subcontractors
6. Shortage in material
7. Labor supply
8. Equipment availability and failure
9. Lack of communication between parties
10. Mistakes during the construction stage

In this study, the analysis was done by considering the total construction industry as a
whole. However the causes and effects of delays can be, vary with the type of the
project. For example, the causes of delays in building construction project can be
different from road construction project. Whereas the causes and effects of project
delays can be, vary from country to country.

Same kind of study was carried out by Alagbari et. al (2007). to identify the main
causes of delays in building construction projects in Malaysia. They have divided the
causes of project delays according to the responsibility. They have initially identified
32 causes of building project delays and categorized them according to the
responsibility of contractor, owner, consultant or extcmal as follows.

1. Contractor's responsibility
1. Delay in delivery of materials to site
11. Shortage of materials on site
111. Construction mistakes and defective work
IV. Poor skills and experience oflabour
v. Shortage of site labour
VJ. Low productivity of labour

15
 v11. Financial problems
vm. Coordination problems with others
IX. Lack of subcontractor's skills
x. Lack of site contractor's staff
XJ. Poor site management
xu. Equipments and tool shortage on site

2. Consultant's responsibility
1. Absence of consultant's site staff
11. Lack of experience on the part of the consultant
111. Lack of experience on the part of the consultant's site staff
(managerial and supervisory personnel)
1v. Delayed and slow supervision in making decisions
v. Incomplete documents
VI. Slowness in giving instructions

3. Owner's responsibility
1. Lack of working knowledge
11. Slowness in making decisions
lll. Lack of coordination with contractors
IV. Contract modifications (replacement and addition of new work
to the project and change in specifications)
v. Financial problems (delayed payments, financial diff:icultics,
and economic problems)

4. External factors
1. Lack of materials on the market
11. Lack of equipment and tools on the market
lll. Poor weather conditions
IV. Poor site conditions (location, ground, etc.)
v. Poor economic conditions (currency, intlation rate, etc.)
VI. Changes in laws and regulations

16

lo.,
 vu. Transpotiation delays
Vlll. Extemal work due to public agencies (roads, utilities and public
services)

The main causes of project delays in Malaysian building construction projects were
identified as follows (Algabari eta!, 2007).

1. Financial difficulties and economic problems

2. Supervision too late and slowness in making decisions
3. Slow to give instructions
4. Lack of materials on market
5. Poor site management
6. Material shmiages on site
7. Construction mistakes and defective work
8. Delay in delivery of materials to site
9. Slowness in making decisions
10. Lack of consultants experience
11. Incomplete documents

The study identified that the financial problems as the main factor in delaying
construction projects from the contractor's as well as owners' point of view. From the
consultants point of view the main factor that contributes to delay in construction
projects was inclfcctive or lack of supervision, followed by slowness of giving
instructions and lack of experience. The most impmiant extemal factor that causes
delays was lack of material, tools & equipments at the site.

The findings of Algabari et. al (2007) was different from that of Sambasivam and
Soon (2007), although both researches were carried out in Malaysia at same time
period. Sambasivam & Soon (2007) used generalized approach whereas Algabari et.
a!. (2007) used specific approach to identify project delays in building construction

17

..
projects in Malaysia. This shows that the causes of project delays can be vary from
project to project.

Asaaf and Al-Hejji (2006) identified causes of delays and their importance in large-
scale construction projects in Saudi Arabia. They identified 73 causes of project
delays by literature survey and interviewing the professionals involved in the
construction industry. They categorized those causes under nine categories as
follows.

1. Project related
1. Original contract duration is too short
II. Legal disputes b/w various parts
111. Inadequate definition of substantial completion
IV. Ineffective delay penalties
v. Type of construction contract (Turnkey, construction only)
v1. Type of project bidding and award (negotiation, lowest bidder)

2. Owner related
1. Delay in progress payments by owner
11. Delay to furnish and deliver the site to the contractor by the
owner
111. Change orders by owner during construction
IV. Late in revising and approving design documents by owner
v. Delay in approving shop drawings and sample materials
v1. Poor communication and coordination by owner and other
parties
VII. Slowness in decision making process by owner
vu1. Conflicts between joint-ownership of the project
IX. Unavailability of incentives for contractor for finishing ahead
of schedule
x. Suspension ofwork by owner

18
 3. Contractor related

1. Difficulties in financing project by contractor

11. Conflicts in sub-contractors schedule in execution of project
111. Rework due to enors during construction
IV. Conflicts b/w contractor and other parties (consultant and
owner)

v. Poor site management and supervision by contractor

VI. Poor communication and coordination by contractor with other
parties

VII. Ineffective planning ami scheduling of project by contractor

Vl!L Tmprq~u c,;,1si.ruCLion methods impkrncdcd by contractor
IX. Delays in sub-contractors work
x. Inadequate contractor's work

XI. Frequent change of sub-contractors because of their i11efficicnt

work

xu. Poor qualification of the contractor's technical staff

XIII. Delay in site mobilization

..J.. Consultant rdatcd

1. Delay in performing inspection and testing by consultant

11. Delay in approving major changes in the scope of work by
consultant
111. lnilexibility (rigidity) of con~;ultant

tv. Puor conm1unication/coorJination bclween consultant and

other parties

v. Late in reviewing and approving design documents by

consulLtnt
VI. Conflicts between consultant and design engineer
VII. Inadequate experience of consultant

19

..
 5. Design related

1. Mistakes and discrepancies in desit,TJ1 documents

II. Delays in producing design documents
lll. Unclear and inadequate details in drawings
1v. Complexity of project design
v. Insufficient data collection and survey before design
VI. Misunderstanding of owner's requirements by design engineer
VII. Inadequate design-team experience
Vlll. Un-use of advanced engineering design software

6. :vraterials related
L ShurLlge of construe lion materials in market
11. Changes in material types and specifications during
construction
lll. Delay in material delivery
IV. Damage of sorted material while they arc needed urgently
v. Delay in manufacturing special building materials
VI. Late procurcmc11t of materials
VII. Late in selection of finishing materials due to availability of
many types in market

7. Equipment related
1. Equipment breakdowns
tl. Shortage of equipment
111. Low level of equipment-operator's skill
1v. Low productivity and efficiency of equipment
v. Lack ofhigh-teclmology mechanical equipment

8. Labors related

1. Shortage of labors
11. Unqualified workforce
111. Nationality of labors

20

L
 1v. Low productivity level of labors
v. Personal conflicts among labors

9. External causes
1. Effects of subsurface conditions (e.g., soil, high water table,
etc.)
11. Delay in obtaining pem1its from municipality
111. Hot weather effect on construction activities
1v. Rain effect on construction activities
v. Unavailability of utilities in site (such as, water, electricity,
telephone, etc.)
v1. Effect of social and cultural factors
v11. Traffic control and restriction at job site
v111. Accident during construction
1x. Differing site (ground) conditions
x. Changes in government regulations and laws
x1. Delay in providing services from utilities (such as water,
electricity)
x11. Delay in perfonning final inspection and ceriification by a third
party

Ranking of CclllS\~S for delays in large construction projects in Saudi Aral;ia were
categorized according to the respondents as table 1.1. (Asaafand Al-Hejji, 2006).

21

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 Table 1.1- Causes of project delays in large construction projects in Saudi Arabia
(Asaaf and Al-Hejji, 2006)

I
Causes identified by Causes identified by Causes identified by
Clients contractors consultants
1 Shortage of labor Delay in progress payments Type of project bidding and
by owners award
2 Unqualified work force Late in reweaving & Shortage of labor
approving of design
documents by owners
3 Ineffective planning by Change orders during Delay in progress payments
contractor -
constructions by owners
4 Low productivity level of Delay in producing design Ineffective planning by
labor documents contractor ·----
5 Hot weather effect on Late in reweaving & Change orders by owner
construction activities approving of design during constructions
documents by consultant
6 Conflicts with sub Difficulties in financing Low productivity level of
contractors _project by contractor labor
7 Poor site management by Mistakes & discrepancies in Difficulties in financing
contractors design documents project by contra_ctor --
8 Inadequate contractor Late procurement of Poor site management by
~xpenence___________ materials contractors ----
r-- -----------------
9 Effects of surface conditions Inf1exibility of consultant Poor qualifications of
---
contmctors technical staff
10 Change orders by owner Slowness of decision making Delay in material delivery
during constructions by owners

Asaaf and Al-Hejji (2006) ranked the causes of delays as follows.

1. Ow·ncr related i~1ctors

2. Contractor related factors

"
.), Design team related factors
4. Labor related factors
5. Consultant related factors
6. Material related factors
7. External factors
8. Project elated factors
9. Equipment related factors

22

L
 Average time ovemm in large construction projects in Saudi Arabia was between
10% and 30% of original duration (Asaaf and Al-Hejji, 2006). Study indicated that
the highest frequency factor for the delay was awarding the contracts to the lowest
bidder. Common cause identified by all the parties was "Change orders by owner
during construction".

Major causes of project delays in large construction projects in Saudi Arabia

identified by Asaaf and Al-Hejji (2006) is different from findings of Sambasivam &
Soon (2007). In Saudi Arabia labour problem is one of the major cause for project
delays (Asaaf and Al-Hejji, 2006), whereas in Malaysia labour problem has obtained
middle level significance (Sambasivam & Soon, 2007). This shows that causes of
project delays can be different from country to country.

Odeh and Battaineh (2002) identified causes of delay in traditional type of contracts
in Jordan. This research was aimed at identifying the main causes for delay in
construction projects with traditional type contracts. Twenty-Eight causes of delays
were identified in traditional construction projects in Jordan and categorized them in
to following major gToups (Odeh & Battaineh, 2002).

1. Client related factors

1. Finance and payments of completed work
11. Owner interference
111. Slow decision making by owners
1v. Unrealistic imposed contract duration

2. Contractor related factors

1. Subcontractors
11. Site management
lll. Construction methods
1v. Improper planning
v. Mistakes during construction
v1. Inadequate contractor experience

23

''

L
 3. Consultant related factors
1. Contract management
11. Preparation and approval of drawings
1n. Quality assurance & control
1v. Waiting time for approval of tests and inspections

4. Material related factors

1. Quality of material
11. Shortage of material

5. Labor & equipment related factors

1. Labor supply
11. Labor productivity
111. Equipment availability and failure

6. Contract related !actors

1. Change orders
11. Mistakes and discrepancies in contract document

7. Contractual relationship related factors

1. Major disputes and negotiations
11. Inappropriate overall org<mization structure linking all parties
to the project
111. Lack of communication among parties

8. External factors
1. Weather conditions
11. Regulatory changes and building code
111. Problems with neighbors
1v. Unforeseen ground conditions

24

....
According to findings ofOdeh and Battaineh (2002) major causes ofproject delays in
traditional construction projects can be ranked as follows.

Table 1.2- Causes ofproject delays in traditional contracts in Jordan (Odeh and
Battainelz, 2002)

Causts identified by consultants Causes identified by contractors

I Inadequate contractor ex12erience Labor productivity problems
2 Finance & payment problems of clients Owner interference
3 Subcontractor related issues Inadequate contractor experience
4 Owner interference Finance & payment problems of
clients ---·--·---
5 Slow decision making by mvners Improper site management by
contractors
6 Unrealistic contract durations given by Improper construction methods by
clients contractors
7 Improper contract management by Equipment availability & failures
consultants --- r---
8 Improper planning by contractor Slow decision making by owners
9 _Labor pro_d ucti v i_!:Y_j2_to bler~~_s________ -Subcontractor related issues
---------------------
f---
10 Shortage of labor Improper planning by contractor

Accordingly, the main factor contributes to delays in traditional construction projects

in Jordan was Jack of labour productivity. This was again different from the
Malaysian studies (Sambasivam & Soon, 2006). This depicts causes of delays can be
varied t!-om country lo country.

Frimpong et. al. (2003) carried out a case study to analyze causes of delays of
groundwater projects in Ghana. Ground water projects consists of ground water
exploration, bore hole drilling, pumping test, water quality analysis and civil works.

Frimpong et. al. (2003) had identified 26 factors for the project delays by taking in to
consideration of a specific ground water project in Ghana. The identified causes of
delays arc as follows.

25
1. Planning and scheduling deficiencies
2. Deficiencies in cost estimates prepared
3. Inadequate control procedures
4. Delays in work approval
5. Waiting for infonnation
6. Mistakes during construction
7. Delays in inspection and testing ofwork
8. Cash flow during construction
9. Frequent breakdowns of construction plant and equipment

10. Shortages of technical personnel

11. Labor shortages
12. Monthly payment difficulties
13. Poor contract management
14. Shortage of materials, Plant/equipment parts
15. Contractor's financial difficulties

16. Low bid

17. l'v1aterial procurem;::'nt
18. Imported materials
19. Late delivery ofmaterials and equipment
20. Escalation of material prices
21. Slow decision-making
22. Inflation
23. Difficulties in obtaining construction materials :1t onicial current prices

24. Ground problems

25. Bad weather
26. Unexpected geological conditions

According to findings of Frimpong ct. al. (2003) ranked causes of delays of ground

water project are as follows.

1. Monthly payment difficulties

2. Poor contract management
3. Material procurement

26
 4. Inflation
5. Contractor's financial difficulties
6. Escalatim1 of material prices
7. Cash flow during construction
8. Planning and scheduling difficulties
9. Bad weather
10. Deficiencies of cost estimate prepared

Findings of Nigeria (Frimpong et. al., 2003) were inline with that of Malaysia
(Sam basi van & Soon, 2006). According to the both of studies, financial problems was
identified as main ca1Jse for project delays. Rese<Jrch carried out by Frim1Jong ct. al.
(2003) did not consider whole construction industry in Ghana. It only considered

about a specific project.

Jayawardane & Pandita (2003) identified 45 L1ctors for project delays of construction
industry in Sri Lanka. They categorized those causes in to 11 categories as follows.

1. Material related factors

1. Shmiage of material

11. Change the type and specifications

111. Slow delivery

1V. Damage in storage on site

2. Manpower
1. Shortage
11. Labour skills
Ill. Labour disputes/Strikes

3. Equipment
Failure

11.
1.

Shortage
... ..
111. Unskilled operation

1V. Slow delivery

27

....
 v. Old machinery

4. Financing
1. Contractor's cash position
11. Delay in payments by clients
111. Delay in certification by consultant

5. Changes
1. Owner I consultant
11. Errors made by consultant
111. Foundation conditions encountered at field
1v. Mistakes in soil investigation
v. Water table condition
v1. Geological condition at the site
v11. Errors committed during construction at site

6. Government relations
1. Obtaining permits from relevant authorities
11. Excessive bureaucracy in Govemment offices

7. Scheduling
1. Preparation and approval of drawings
11. Lack of training of management to model the construction

operation
111. Lack of data base in estimating duration and resources
1v. Inadequate early planning

8. Controlling
1. Waiting for sample approval
11. Inspection and testing procedure

28
 9. Environment
1. Rainy weather
II. Social and cultural factors
111. Limited working hours

l 0. Contractual Relationship
1. Conflicts between contractor and consultant
II. Uncooperative owner
III. Slowness of owner's decision making process
IV. Joint ownership
v. Poor organization of contractor and consultant
VI. Difficulties of coordination and insufficient communication
VII. Delay due to sub contractor
Vlll. Delay due to lack of facilities to sub contractor
IX. Unavailability of professional construction management team
x. Legal disputes between parties involved in the project

11. Location of site

1. Access to the site
II. Surrounding
111. Lack of area for operation/ material stocks

According to Jayawarclane & Pandita (2003), main delaying factor identified was
rainy weather. Since Sri Lanka is a tropical country, this can be well acceptable. The
other main causes of project delays identified by them were "Design changes by
owners & consultants" and "Manpower shortages". Jayawardane & Panditha (2003)'s
findings were generalized to the building construction projects in Sri Lanka.

Project size, which measured in m 2 gross external floor area, and project standard,
which measured in building construction cost/m 2 gross external floor area are founded
as significant drivers of construction speed in residential building projects in

29
I
I.

L
 Gcnnany (Stoy et.al., 2007). This shows that the speed of construction can be vary
with the type of the project.

The causes of delays can be varied according to following factors.

l. Geographical location of the project

2. Type of the construction project

3. Method of the construction project (i.e. traditional construction projects, Turn

key projects, etc.)

2.4 Studies on Effects due to construction delays

Aibinu and Jagboro (2002) identified the efCects of construction delays in Nigeria.
The identified effects due to project delays in Nigeria are as follows,

l. Time ovenun
2. Cost ove1Tun
3. Disputes
4. Arbitration
5. Litigation
6. Total abandonment
According to their analysis ranking of eiiects of project delays were as follows

(Anibu and Jagboro 2002).

1. Time overrun
2. Cost overrun
"j , Disputes

4. Total abandonment
5. Arbitration
6. Litigation

30

~
Effects of the delays in construction projects can be changed according to the type of
project (Samabasivan & Soon, 2006). For example, delays in infrastructure
development project like southem high way will cause huge economic loss to the
whole country, whereas delay in construction of house can only affect to the

respective client.

Sambasivan & Soon (2007) adopted same effects of project delays identified by
Anibu and Jagboro (2002). The ranking of effects due to project delays in Malaysian
construction industry as follows (Sambasivan & Soon, 2007).

1. Time overrun
2. Cost overrun
3. Disputes
4. Arbitration
5. Litigation
6. Total abandonment

Although the first two effects due to project delays were identical in Malaysia
(Sambasivan & Soon, 2007) and in Nigeria (Anibu & Jagaboro, 2002) "total
abandonment" was more prominent in Nigeria. In Malaysia, "total abandonment" was
categorized at last. This shows that the effects due to project delays can be varied

from lhe country to country.

2.5 :Methods to minimize project delays

Most of studies identified that the improvement of 'contractors managerial skills' was
one of the basic needs to reduce project delays Fringpong et.al. (2003) suggested
introducing continuous training programs to contractors' managerial staff as a

solution.

31

...;,.:
To reduce the selecting of incapable contractors at bidding stage Sambasivan & Soon
(2007) suggested introducing different selection process that gives more weight to
capabilities rather than the price of the bid.

''Change orders" is one of the major factors contributes to delays. To reduce delays
most of the studies suggested to minimize the change orders (Sambasivan & Soon,
2007; Assaf & Al-Hejji, 2006; Jayawardane & Pandita, 2003).

Fringpong et.al. (2003) suggested, introducing effective and efficient material

procurement system at the site level to minimize the shortage of materials at site.

To mitigate the delays occmTing due to approval of drawings Assaf and Al-Hcjji
(2006) suggeskd consultants to minimize the delays in the approval process.

Sambasivan and Soon (2007) suggested contractors to appoint able site managers for
the smooth execution ofwork .Since the site managers should plan the work program

according to day to day conditions they should be capable of handling those projects
with good project management skills.

To minimize the delays due to changes in weather conditions Jayawardane & Pandita
(2003) suggested to consider the weather pattems at the initial planning stage of the
project.

Since the 'shortage of labour' is a huge problem in construction industry

encouragement of existing workers to acquire new specialized skills was suggested
by Jayawardanc & Pandita (2006) after considering the construction industry in Sri
Lanka.

Aibinu and Jagboro (2002) suggested two methods to minimize project delays. First
was accelcralion of site activities and the second was to increase the contingency
allowances.

32
 2.6 Relative Important Index

Sambasivan & Soon(2007), Jayawardane & Pandita (2003), and Abinu & Jagoor
(2002) used the relative impmiant index to determine the relative importance of the
causes of project delays.

They have adopted five point Liket scale to define the importance of the causes. The
relative importance index as follow.

RJI = 'j_yj_

A*N

Where 'W' is the weighting given to each factor by the respondent (ranging fi"om 1 to
5), 'A' is the highest weight (i.e. 5), and 'N' is the total number of respondents. 'RII'
value had a range from 0 to 1. Higher value of RII gives higher significance for the
cause.

Frimpong et. al. (2003) used same method to analyze the significance of causes.
However, he names it <lS "relative impotiant weight".

Assaf & AI. Hejji (2007) used diiierent approach to calculate the importance of the
causes. He defined "Frequency Index" and "Severity Index" as follows.

Frequency Index (FI) =I a (n/N) * 100 /4

Where "a" is the constant expressing the weight given by each respondent, "n" is the
fi:cqucncy of tilt.? n;spon::;c, a1:d "N" i:; total number of rcspor;ses. Frequency index
was used to categorize causes according to frequency of occurrence.

Severity Index (SI) =I a (n/N) * 100 /4

Where "a" is the constant expressing the weight given by each respondent, "n" is the
frequency of the response, and "N" is total number of responses. Severity index was
used to categorize causes according to the severity of occurrence.

The importance of each cause is based on the frequency and severity of it. Therefore,
Assaf & A!. Hcjj i (2007) defined relative important index as follows.

33

l
Relative Importance Index (RII) = FI * SI

Assaf & AI. Hejji (2007)'s approach of calculating relative impotiance index is better
than that of the other researchers'. Respondent has to answer two questions for one
cause (i.e. frequency of occunence and degree of severity), it gives more realistic
picture about the causes of delays.

2.7 Spearman's Rank Correlation Coefficient

The objective of rank conelation methods is to assess the degree of monotonicity

bct\veen two or more series of paired data (Costa & Roque, 2006). Conelation can be
defined as relationship measure among different parties of factors. It gives the
strength of their relationships. Speannan's rank correlation coefficient IS a non-
parametric test. (Distribution free tests) These tests have the obvious advantage of not
requiring the assumption of normality or the homogeneity variance (Assaf & Al-
Hejji, 2006).

Speam1an's rank correlation coefficient can be defined as follows, when there are no
tied ranks.

p = 1 - 6} d 2 ~ .f•. . .../'.•;\\
'(.

&.

• •
, .,
~¥#'1M
t
111:
(>"'
.
-;.-,.

2
n (n -1) .
\ :>

\_:: --.:~:...
Where, 'd' is the difference in the rank of the values of each matched pair and 'n' is
the Number of pairs of rank.

If tied rank exists, speannan' s rank conelation coefficient can be defined as follows,

p= -----=-----=----·----'1'-"--1
,__CI'-"-x.jyi) - cIxD C">'vi
[ n ( Ixi 2) 2 - ( LXi 2? r' 2 [ n ( LYi 2) 2 - ( I y?) 2 Y2

34
Where, X; is the rank given by first group, y; is the rank given by second group and n
is the number of pairs of ranks.

In spearman's rank correlation coefficient if concordance is perfect p = 1 If

discordance is perfect p = -1. The value of p in all other cases lies between these
limits (O'Brien & Griffiths, 1965). Spearman's rank conelation coefficient equal to 1
indicate the perfectly positive correlation. p= -1 indicates perfectly negative
correlation. p= 0 indicates no correlation among the pariies.

To check whether the value obtained for the spearman's rank conelation coefficient
could be a result of chance, significance level of the relationship is used. This
signilicance level can be checked by using a graph, which shows significant level and
the degree of freedom (Appendix 3). If the results are above 0.1% significance level,
it can be 99.9% confident that the correlation has not occurred by chance. If the
results are above 1% significance level, it can be 99 % confident that the correlation
has not occurred by chance.

2.8 Chapter Summary

There were quite a large number of researches were carried out in the world to
identify causes of project debys and as well as there effects. The causes can be varied
with the typ,:; or tlw projeLt. Although there were few rescarcht:s i11 Sri Lu1ka to
identify the causes of project delays, no evidence was found regarding researches on
their effects. Most of the researchers were used 'relative important index' method to
identify the importance of the project delays. Those studies recommended
'improvement of project management skills of the contractors' staff, 'minimization
of change orders', 'introduction of efficient material procurement', etc. to reduce
project delays.

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