Nyoman Rowin Sinaya, Parwadi Moengin, Bambang Endro Yuwono, Darmawan Pontan 
Jurnal Indonesia Sosial Teknologi, Vol. 5, No. 6, Juny  2024                                                 2806 
 
Figure 1 Cost quote normal distribution graph 
 
Normal Single Distribution 
The formula for calculating the probability of winning is the same as Equation 3. 
The difference with normal multi-distribution is that in a normal single distribution, the 
probability  of  winning  is  calculated  against  the  average  of  all  competitors  (Average 
Bidders) or only on one bid data set, namely the lowest bid data set. 
 
Method 
Data Collection Methods 
This study used primary data collection methods and secondary data. Primary data 
was obtained from the construction company PT Nindya Karya, which had bidding data 
in the period 2021 to 2023 on infrastructure projects with project values between IDR 100 
billion and IDR 300 billion, as well as competitor bid data. Meanwhile, secondary data 
are data obtained from literature sources such as course materials, websites, the internet, 
scientific  papers/journals,  books,  Electronic  Procurement  Services  (LPSE)  of  the 
Ministry of PUPR, and other sources that have something to do with this research.  
Data Processing Method with Statistical Approach 
The initial step in data processing with statistical approach methods is to determine 
the method used, namely by using three methods: multi-discrete distribution method, 
normal multi-distribution, and normal single distribution. The data converted into ratios 
is  then  grouped  from  smallest  ratio  and  largest  ratio.  After  that,  the  mean,  standard 
deviation,  and  variance  for  normal  multi-distribution  and  normal  single  distribution, 
while discrete multi-distribution uses the initial ratio that has been analyzed, are found. 
The result of this data processing is the probability of each contractor winning. In the 
multi-discrete distribution  method,  a  histogram  or  analysis  from the  Microsoft  Excel 
program is used, which is the same. In contrast, in the multi-normal distribution method, 
a single normal distribution is used in the Z cumulative normal distribution table. 
Bidding Strategy Model Data Processing Method 
After finishing calculating all probability of winning using the statistical approach 
of multi-discrete distribution, multi-normal distribution, and single normal distribution, 
then the next step is to calculate the optimum Mark up and maximum Expected Profit 
using three bid strategy models, namely the Friedman model, Gates model, and Ackoff 
&; Sasieni model. After that, a comparison chart is made between the Expected Profit 
against the Mark of each model. 
Model Testing With Optimum Mark-Up 
The optimum markup obtained from the calculation process will be tested against 
the  bid  prices  by  seeing  whether  it  will  be  lower  (which  means  winning)  or  higher 
(meaning losing) than the lowest bid price. The bid hypothesis is obtained by multiplying 
the  estimated  cost  of  the  contract  by  the  markup  of  the  calculation  result  and  then 
comparing it with the lowest bid from the winning contractor. The data used in this test 
is the data of 24 project tenders used by the sample in this study, which will be tested for