In construction cost planning, probabilistic estimating incorporates uncertain inputs such as labour availability, labour productivity, and the applicable wage scale to quantify risk and expected cost—what does it typically include?

Difficulty: Easy

Correct Answer: All of these

Explanation:


Introduction / Context:
Probabilistic estimating (also called risk-based or range estimating) recognises that construction project inputs are uncertain. Rather than a single-point number, it models a distribution of possible costs by considering variability in labour, productivity, and wage rates, along with other drivers. This question checks whether you understand the key inputs that must be treated as random variables in such an estimate.


Given Data / Assumptions:

  • The project involves activities whose costs are influenced by labour hours and output rates.
  • Observed variability exists in crew productivity due to learning curves, weather, congestion, and access conditions.
  • Wage scale (including basic pay, allowances, and statutory burdens) can differ by trade, shift, and location.


Concept / Approach:
In probabilistic estimating, inputs are represented by probability distributions (e.g., triangular, beta-PERT, or normal). Monte Carlo simulation, or simpler range analysis, then propagates these uncertainties to the total cost. Key cost elements—crew composition (labour), their productivity (units per hour), and wage scale (₹/hour)—directly drive activity costs, so all must be included with uncertainty ranges, not as fixed values.


Step-by-Step Solution:

Identify cost drivers for each activity: labour hours = quantity / productivity.Assign distributions to productivity (e.g., optimistic, most likely, pessimistic) and to wage scale where escalation or shift differentials apply.Run a simulation or analytical propagation to obtain a distribution of total cost and percentiles (P10, P50, P90).


Verification / Alternative check:

Benchmark results against historical projects with similar complexity; confirm that the P50 aligns with typical outcomes and P90 incorporates realistic contingency.


Why Other Options Are Wrong:

Selecting only labour, only productivity, or only wage scale ignores other equally critical sources of variability; a robust probabilistic estimate must incorporate all listed inputs.'None of these' contradicts the foundations of risk-based estimating.


Common Pitfalls:

Using single-point productivity factors; failing to separate base wage from burdens; ignoring shift or overtime multipliers that widen the uncertainty.


Final Answer:

All of these

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