On February 6, 2009, President Barack Obama signed Executive Order 13502, which asks federal authorities to consider using LTOs for federal construction projects that cost $25 million or more.  The purpose of this act was to repeal Bush`s executive orders in 13202 and 13208, over the previous eight years, which had banned mandatory PLAs for federal and federal projects.  The Obama Order states that federal authorities may require a PLA if such an agreement meets the federal government`s objectives in terms of profitability and efficiency. Under the terms of the contract, contractors cannot compete for contracts subject to PLA, but they must accept the different conditions contained in each ALP to win a federal contract and build a project.  A significant change from the 2001 order is that the Obama order, by removing bush sponsors from federal funds, such as public, local and private owners, allows for the use of public construction projects of all sizes. The order does not encourage or instruct federal aid recipients to use a government-mandated PLA.  An independent study conducted in 2011 by the National University System Institute for Policy Research analyzed the impact of GPs on school construction in California from 1996 to 2008.  The study analyzed 551 school construction projects and is reported to be the largest study on LTAs to date.  It found that the use of PLA increased construction costs by 13-15%, which would represent an increase of $28.90 to $32.49 per square metre if adjusted for inflation.  However, the findings of this study were vigorously challenged by Dr.
Dale Belman of Michigan State University, a long-time supporter of the use of PLA, whose previous research has been mentioned several times and who stated that the study misrepres shot its results. He wrote to the authors: “Although your study has serious statistical problems, your results are ultimately consistent with the results on LTCs and Massachusetts school construction costs. The summary of your results can be summarized as follows: if appropriate controls are included for differences between the characteristics of built schools, including the type and location of the school, construction specifications, materials used, etc., there is no statistical evidence that PLA schools are more expensive than non-PLA schools.” The authors of the study indicate in the report that they used robust regression methods to account for deviations in school materials/techniques and construction sites. Robust regression is a statistical technique used in combination with predictive models when the data set has no normal distribution or where there are significant outliers that can distort the results of a standard regression test. In a robust regression analysis, the influence of outliers is weighted downwards, allowing for more statistical relationships in the results. 2. Amounts are calculated by multiplying the reasonable hourly rates prescribed in the flight plan by the number of hours worked directly.