## 5 Discussion  
### Project Scope Decomposition  
Building an EIBS might be one of the most challenging and time-consuming parts of a preliminary estimation. This is mostly caused by quite high uncertainty and limited time.  
\begin{table}
\begin{tabular}{l c c c} \hline \hline  & **Manual** & **Optimized** & **Manual–Optimized** \\ \hline Duration, months & 6.5 & 5.5 & \(-\)1.00 (\(-\)15.4\%) \\ Team FTE & 15.00 & 15.75 & +0.75 (+5.0\%) \\ Development FTE & 7.50 & 9.00 & +1.50 (+20.0\%) \\ ND-FTE & 7.02 & 8.48 & +1.46 (+20.8\%) \\ Normalized cost & 12,285.00 & 10,395.00 & \(-\)1890.00 (\(-\)15.4\%) \\ \hline \hline \end{tabular}
\end{table}
Table 10: Comparison of the manual and optimized optimistic estimates for RTPPM-E.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multirow{2}{*}{**AHP Rank**} & \begin{tabular}{c} **Duration** \\ **(\(L\))**, **Months** \\ \end{tabular} & \begin{tabular}{c} **Norm. Cost** \\ **(\(F\))** \\ \end{tabular} & \begin{tabular}{c} **NDC (\(C\))**, **Man-Hours** \\ \end{tabular} & \begin{tabular}{c} **NDC-NDE**, **Mean-Hours** \\ \end{tabular} & \
\begin{tabular}{c} **Team FTE** \\ **(\(\phi^{\text{\tiny B}}\))** \\ \end{tabular} &
\begin{tabular}{c} **Develop.** \\ **FTE (\(\phi^{\text{\tiny B}}\))** \\ \end{tabular} \\ \hline
1 & 0.075 & 6.5 & 18,099.90 & 3653.33 & 110.53 & 23.25 & 13.50 \\
2 & 0.072 & 9.5 & 17,955.00 & 3561.60 & 16.80 & 15.75 & 9.00 \\
3 & 0.070 & 7.0 & 18,690.00 & 3627.03 & 82.23 & 22.25 & 12.50 \\
4 & 0.068 & 9.0 & 18,711.00 & 3589.01 & 44.21 & 17.00 & 9.50 \\
5 & 0.068 & 11.0 & 18,942.00 & 3637.64 & 92.84 & 14.25 & 8.00 \\ \hline \hline \end{tabular}
\end{table}
Table 8: Top alternatives for the RTPBM-E pessimistic estimate.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Identifier (\(m\))**} & \multirow{2}{*}{**Type \({}^{\star}\)**} & **Role** & **FTE (\(\phi^{\text{\tiny B}}\))** & **CLPC (\(\omega^{\text{\tiny B}}\))** & **IPC (\(\varphi^{\text{\tiny B}}\))** & **PC (\(\varphi^{\text{\tiny B}}\))** & **ND-FTE (\(\phi^{\text{\tiny B}}\))** \\ \hline
1 & D & Senior developer & 1 & 12 & 0.9 & 1.08 & 1.08 \\
2 & D & Middle developer & 6 & 1 & 1 & 1 & 6 \\
3 & D & Junior developer & 2 & 0.7 & 1 & 0.7 & 1.4 \\
4 & ND & Project manager & 1 & n/a & n/a & n/a & n/a \\
5 & ND & Technical leader & 1 & n/a & n/a & n/a & n/a \\
6 & ND & Business analyst & 1 & n/a & n/a & n/a & n/a \\
7 & ND & UK designer & 0.75 & n/a & n/a & n/a & n/a \\
8 & ND & DevOps engineer & 0.5 & n/a & n/a & n/a & n/a \\
9 & ND & Test engineer & 2.5 & n/a & n/a & n/a & n/a \\ \hline \hline \end{tabular}  
* D and ND stand for “development” and “nondevelopment”, respectively.  
\end{table}
Table 9: Optimized team composition for RTBPM-E.  
Despite this, it is necessary to break down the project scope at a high level without diving into details but, at the same time, covering all of the functionality of the future project.  
Working with an EIBS includes these three main steps: (a) decomposition; (b) analysis; (c) sizing. Each of them is related to the necessity of processing a quite large amount of information under time restrictions. In this regard, the following mistakes are possible: (a) missing significant parts of the project functionality; (b) blowing up the scope by including unnecessary features; (c) incorrect structuring of the project scope, which can be difficult to elaborate on during the next estimation stages.  
These are some recommendations that can help with the challenges mentioned above:  
1. Use a project scope visualization that makes the perception and analysis of large amounts of information easier.
2. Cover the unknown with assumptions and risks.
3. Add placeholder EIs to cover the unknown parts of the functionality.
4. Use EIBS templates based on historical estimates and projects.  
Methods of building an EIBS still require further research and testing in practice.