国会预算办公室-国会预算办公室解释了立法成本估算中常见的不确定性来源（英）-2025.2_6页_1mb

Summary of CBO Budget Primer on Uncertainty in Cost Estimates

Overview

The Congressional Budget Office (CBO) provides cost estimates for legislation by producing point estimates, which represent the middle of the most likely budgetary outcomes. This document explains six common sources of uncertainty that CBO considers in these estimates and how the agency addresses them. Uncertainty arises from various factors, and CBO uses its best judgment and available data to inform cost estimates, guiding lawmakers in deliberations and budget enforcement.

Sources of Uncertainty and CBO's Approach

1. Broad Legislative Language

• Description: Vague language in legislation leaves implementation decisions to the executive branch, which may differ from CBO's assumptions.
• CBO's Approach: Considers potential interpretations from Congressional staff and agencies to assess likely implementation methods and refine projections.

2. Budget Projections Under Current Law

• Description: Uncertainty in macroeconomic forecasts (e.g., recessions, inflation) and program spending dynamics affects baseline projections.
• CBO's Approach: Updates projections based on existing data and economic indicators, acknowledging that real-world changes can alter outcomes, and incorporates adjustments for events like the COVID-19 pandemic.

3. Insufficient Data or Research Material

• Description: Lack of comprehensive data, measurement errors, or limited historical patterns makes cost predictions harder for new or emerging programs.
• CBO's Approach: Uses information from multiple sources, fills gaps with expert input, and considers volatility in data to estimate a range of possible responses.

4. Varied Eligible Population

• Description: Difficulty in precisely estimating the size and composition of groups eligible for benefits under new or amended programs.
• CBO's Approach: Leverages demographic data, agency reports, and historical patterns to gauge eligibility, focusing on clear criteria to assess potential cost impacts.

5. Behavioral Responses

• Description: Uncertainty about how individuals or entities will respond to policy changes, such as accepting new benefits or enacting regulations.
• CBO's Approach: Draws from research and past experiences to predict behaviors, estimating probabilities of various outcomes in the middle of the likely distribution.

6. Dependence on a Future Event

• Description: Legislation may create programs linked to unpredictable events, such as natural disasters or economic shifts.
• CBO's Approach: Uses historical data to estimate likelihoods and timing of events, and considers scenarios to assess potential budgetary effects when data is limited.

This primer aids Congress in making informed budget decisions by highlighting the factors CBO considers in minimizing uncertainty.