A linear regression modelling of the relationship between initial estimated and final achieved construction time in South Africa

View/ Open
Date
2012Author
Aiyetan, Olatunji Ayodeji
Smallwood, John
Shakantu, Winston
Metadata
Show full item recordAbstract
English: The estimation of contract completion time has always been inaccurate despite there being a need for certainty regarding the completion of projects. This article reports on an investigation of the relationship between initial and final contract time with the aim of developing an equation for reasonably estimating project period. Data for the study was secured from a total of eighty-eight questionnaires and sixty-five projects. The sample population consisted of architects, contractors, quantity surveyors, structural engineers and clients. Five metropolitan cities in the provinces of the Eastern Cape, Free State, Gauteng, KwaZulu-Natal, and the Western Cape, namely Bloemfontein, Cape Town, Durban, Johannesburg and Port Elizabeth, constitute the geographical area in which the study was conducted. Inferential statistical analysis, including regression analysis, was used to evolve, inter alia, a model and linear equations for estimating building construction time. The equations involved in the respective phases of the study are Y = 9.9 + 1.0586x for phase one, and Y = 13.1159 + 1.1341x for phase two. During phase two of the study, it was determined that 35.3% additional time needs to be added to the amount of the initial contract period in order to estimate final contract time. It is recommended that either the equation Y = 13.1159 + 1.1341x be used, or that 35.3% additional time be added to the amount of initial contract time to estimate the final contract time. Afrikaans: Die skatting van die konktrakvoltooiingstydperke was altyd inkorrek ten spyte
daarvan dat daar ‘n behoefte is vir sekerheid betreffende die voltooiing van
projekte. Hierdie artikel doen verslag oor ‘n ondersoek na die verhouding tussen
aanvanklike en finale kontraktydperke met die doel om ‘n berekening vir redelike
geskatte projekperiodes te ontwikkel. Data vir die studie is verkry uit ‘n totaal
van agt en tagtig vraelyste en ses en vyftig projekte. Die steekproefpopulasie
het bestaan uit argitekte, kontrakteurs, bourekenaars, strukturele ingenieurs
en kliënte. Vyf metropoolstede, in die provinsies van die Oos-Kaap, Vrystaat,
Gauteng, KwaZulu-Natal en Wes-Kaap, naamlik Bloemfontein, Kaapstad,
Durban, Johannesburg en Port Elizabeth, het die geografiese gebied gevorm
waarin die studie gedoen is. Inferensiële statistiese analise, insluitende regressive
analise is gebruik om, onder andere, ‘n model en lineêre vergelykings om boukonstruksie
tydperke te skat, te ontwikkel. Die vergelykings wat ontwikkel is in die
onderskeie fases van die studie is Y = 9.9 + 1.0586x vir fase een, en Y = 13.1159 +
1.1341x vir fase twee. Gedurende fase twee van die studie, is dit vasgestel dat
35.3% addisionele tyd tot die aanvanklike kontrakperiode bygevoeg behoort te
word om die finale kontraktydperk te kan skat.
Daar word aanbeveel dat die vergelyking Y = 13.1159 + 1.1341x eerder
gebruik word, of dat 35.3% addisionele tyd tot die getal van die aanvanklike
kontraktydperk bygevoeg word om sodoende die finale kontraktydperk te
kan skat.