ASTM E3372-23 - Standard Guide for Schedule Performance Index, Schedule Beta (β<inf>s</inf >)

1.1 This guide covers schedule beta (β_s), which measures construction project participant schedule performance versus that of the overall completed project and is based on beta (β) from financial portfolio theory for measuring the correlation between individual stock performance and that of the overall stock market.2 By correlating the delta of actual activity performance (“as-built”) minus that originally scheduled (“as-planned”) to the delta of as-built minus as-planned for the overall completed project for a participant’s collection of projects over a specified period of time, a schedule performance index is established in a similar manner as the aforementioned beta (β) of an individual stock.

1.2 Schedule beta (β_s) measures, as a unitless index value, schedule participant (“subcontractor’s”) performance—ahead or behind—as-planned duration as correlated to its respective overall project’s schedule performance.

1.3 Schedule beta (β_s) is measured with input from at least two (2) independent (mutually exclusive) projects that have reached completion, within the defined period of observation.

1.4 Schedule beta (β_s) is measured across a standard predetermined period of time, in similar fashion to that of the insurance industry’s experience modification rate’s (EMR) most recent two (2) complete calendar years within the past thirty-six (36) months.

1.5 Schedule beta (β_s) evaluates schedule participant’s (“subcontractor’s”) most recent performance, not its complete history, such that is it indicative of current performance and contemporary influences—market, geographic, industry trade, etc.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.