Statistical Productivity Improvement Study Results


These statements are based on the statistical findings of PER's Statistical Productivity Improvement (SPI) work sampling procedure for five (5) projects. The study utilized a bootstrapping procedure to calculate the standard errors and confidence intervals at a 95% level for each SPI category and subcategory. All differences in sample averages are based off of the collected samples and the subsequent resampled dataset. This document is without warranty and the user agrees to hold the author and PER harmless for any direct or indirect damages.

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PER analysts have observed as much as a 31.7% reduction in SPI Empty Travel from baseline study to follow-up study.


From project baseline study to follow-up study, PER analysts found that 92.9% of observed project areas had realized a statistically significant reduction in SPI Empty Travel. Empty Travel is defined as walking or riding empty-handed, outside of immediate workface. This change accounted for an average of 3.9 percentage points and a reduction of 31.7%. Through better site logistics and work flow process, project teams are realizing the true potential of their workforce.


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SPI studies have found as much as a 27.7% increase in Statistical Productivity Improvement (SPI) Direct Activity.


From baseline study to follow-up study, PER analysts observed an average increase of 8.5 percentage points in SPI Direct Activity levels for a gain of 27.7%. During this study, 71.4% of observed project areas realized a statistically significant gain in Direct Activity. Direct Activity is defined as all physical productive work (e.g., walking inside of immediate workface, picking up or lying down of tools while performing productive work). By reducing project delays and eliminating bottleneck to key resource process, clients are increasing productivity.


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PER analysts have observed as much as a 60.9% decrease in Statistical Productivity Improvement (SPI) Planning Delay.


PER analysts have observed a 60.9% decrease in SPI Planning Delay from baseline study to follow-up study. Of the contractors observed in the study, 100.0% had a statistical significant decrease in Planning Delay. Planning Delay is defined as crews ready to work but on hold due to waiting for instructions, drawings, or information, among other reasons. At the conclusion of the baseline study, PER analysts provided sound recommendations on reducing costly delays and a path forward to success.


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Project teams have reduced Statistical Productivity Improvement (SPI) Tool & Equipment Delay by as much as 74.9%.


PER analysts observed a 74.9% or 0.8 percentage point decrease in SPI Tool & Equipment Delay between baseline study and follow-up study. Tool & Equipment Delay is defined as crews ready to work but on hold due to immediate unavailability of tools or equipment. This decrease occurred at a statistically significant level for 50.0% of the observed areas. Through better planning of resources and improved site logistics, clients are reducing unproductive waste from their projects.


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PER analysts have found as much as a 35.4% decrease in Statistical Productivity Improvement (SPI) Internal Delay between studies.


On a previous project, PER analysts observed a decrease of 35.4% in SPI Internal Delay from follow-up study two to follow-up study three. Internal Delay is defined as delays due to scheduling conflicts within a crew, excessive craft density, among other reasons. This decrease of 3.7 percentage points occurred at a statistically significant level across 75.0% of the observed project areas. By balancing crew sizes and improving work plans, foremen are reducing the amount of time crews standby idle and unproductive.


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SPI studies have found as much as a 31.8% decrease in SPI Delay, providing clients with the opportunity for increased productivity.


PER found between studies a decrease in SPI Delay by 31.8%. Delay is defined as any activity that is not required to advance work and is one of the three main SPI categories. This reduction in waste occurred at a statistically significant level across 75.0% of the project areas, for an average savings of 7.6 percentage points. As project teams address the identified barriers for uninhibited workflow, clients are realizing significant improvement in their project's productivity.


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Project teams have realized as much as a 36.0% decrease in SPI Personal Delay between follow-up studies.


Between follow-up studies, PER analysts have observed a 36.0% decrease in SPI Personal Delay. Personal Delay is defined as all delays due to personal reasons (e.g., unathorized breaks, smoking, getting vending items out of break times). This average of a 3.6 percentage point decrease was observed at a statistically significant level for 50.0% of the observed project areas. As foremen are provided the necessary resources to manage their crews at critical times of the day, project performance improves without adding additional manpower.


Disclaimer: All results are based on a five (5) project case study of PER's Statistical Productivity Improvement (SPI) work sampling procedure. The statistical methodology for calculating all provided findings utilize 95% confidence intervals from a bootstrapped dataset. Due to the number of uncontrollable variables, PER in no way guarantees the improvement in project performance.