The final cost of public school building projects, like other construction projects, is unknown
to the owner till the account closure. Artificial Neural Networks (ANN) is used in an attempt to
predict the final cost of two story (12 classes) school projects under lowest bid system of award
before work starts. A database of (65) school projects records completed in (2007-2012) are used to
develop and verify the ANN model. Based on expert opinions, nine out of eleven parameters are
considered to have the most significant impact on the magnitude of final cost. Hence they are used as
model inputs while the output of the model is going to be the final cost (FC). These parameters are;
accepted bid price, average bid price, estimated cost, contractor rank, supervising engineer
experience, project location, number of bidders, year of contracting, and contractual duration. It was
found that ANN has the ability to predict the final cost for school projects with very good degree of
accuracy having a coefficient of correlation (R) of (91%), and an average accuracy percentage of
(99.98%).
11. Where: A = actual value, E = estimated or predicted value, n = total number of cases (6 for
validation).
2. Root Mean Squared Error:
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3. Mean Absolute Percentage Error:
%
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4. Average accuracy percentage (AA %) [9]:
AA% = 100% -MAPE
5. The Coefficient of Determination (R2)
6. The Coefficient of Correlation (R).
The results of these statistical parameters are shown in table (6).
Table (6): Statistical Measures Results
Description Statistical parameters
MPE 0.23%
RMSE 0.12
MAPE 0.014%
AA% 99.98%
R2 83 %
R 91%
To assess the validity of the derived equation of the ANN model in predicting the final cost
of a school project (FC), the natural logarithm (Ln) of predicted values of (FC) are plotted against the
natural logarithm (Ln) of measured (observed) values for validation data set as shown in fig. (4). It is
clear from this figure that the resulted ANN has a generalization capability for any data set used
within the range of data used in the training phase. It is a proven fact that neural nets have a strong