project-estimation

SKILL.md

Project Estimation

Table of Contents

Overview

When to Use

Quick Start

Reference Guides

Best Practices

Overview

Accurate project estimation determines realistic timelines, budgets, and resource allocation. Effective estimation combines historical data, expert judgment, and structured techniques to minimize surprises.

When to Use

Defining project scope and deliverables

Creating project budgets and timelines

Allocating team resources

Managing stakeholder expectations

Assessing project feasibility

Planning for contingencies

Updating estimates during project execution

Quick Start

Minimal working example:

# Three-point estimation technique for uncertainty

class ThreePointEstimation:
    @staticmethod
    def calculate_pert_estimate(optimistic, most_likely, pessimistic):
        """
        PERT formula: (O + 4M + P) / 6
        Weighted toward most likely estimate
        """
        pert = (optimistic + 4 * most_likely + pessimistic) / 6
        return round(pert, 2)

    @staticmethod
    def calculate_standard_deviation(optimistic, pessimistic):
        """Standard deviation for risk analysis"""
        sigma = (pessimistic - optimistic) / 6
        return round(sigma, 2)

    @staticmethod
    def calculate_confidence_interval(pert_estimate, std_dev, confidence=0.95):
        """
        Calculate confidence interval for estimate
        95% confidence ≈ ±2 sigma
        """
        z_score = 1.96 if confidence == 0.95 else 2.576
// ... (see reference guides for full implementation)

Reference Guides

Detailed implementations in the references/ directory:

Guide
Contents

Three-Point Estimation (PERT)
Three-Point Estimation (PERT)

Bottom-Up Estimation
Bottom-Up Estimation

Analogous Estimation
Analogous Estimation

Resource Estimation
Resource Estimation

Estimation Templates
Estimation Templates

Best Practices

✅ DO

Use multiple estimation techniques and compare results

Include contingency buffers (15-25% for new projects)

Base estimates on historical data from similar projects

Break down large efforts into smaller components

Get input from team members doing the actual work

Document assumptions and exclusions clearly

Review and adjust estimates regularly

Track actual vs. estimated metrics for improvement

Include non-development tasks (planning, testing, deployment)

Account for learning curve on unfamiliar technologies

❌ DON'T

Estimate without clear scope definition

Use unrealistic best-case scenarios

Ignore historical project data

Estimate under pressure to hit arbitrary targets

Forget to include non-coding activities

Use estimates as performance metrics for individuals

Change estimates mid-project without clear reason

Estimate without team input

Ignore risks and contingencies

Use one technique exclusively