Patrick O’Shaughnessy
Iowa City
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Articles by Patrick O’Shaughnessy
Mathematical optimization of filters used in N95 filtering facepiece respirators
Abstract The filter used in an N95 filtering facepiece respirator (FFR) has a collection efficiency and pressure drop that are primarily influenced by filter depth and solidity, as well as the average diameter and electrostatic charge of its fibers. A sensitivity analysis was performed to determine the influence of each property on particle collection efficiency at the most penetrating particle size (MPPS) and pressure drop using previously verified N95 FFR filter performance models.
The quiet rise of private equity in healthcare: What’s at stake?
Dr. Patrick O’Shaughnessy is president and CEO of Catholic Health of Long Island in New York. (Catholic Health of Long Island/Adobe Stock) DP By Dr. Patrick O’Shaughnessy September 24, 2025 07:54 PM Key Takeaways Private equity is reshaping U.S. healthcare, destabilizing nonfprofit hospitals and widening inequities. Private equity firms have been buying up healthcare entities at a rapid pace.
Validation of N95 respirator models for pressure drop and particle capture efficiency
Abstract Despite efforts to apply administrative and engineering controls to minimize worker exposure to aerosols, filtering facepiece respirators (FFRs) continue to be an important form of personal protective equipment in hard-to-control settings such as healthcare, agriculture, and construction.
Custom Indexing: The Next Evolution of Index Investing
By Patrick O’Shaughnessy December 2020 Download PDF By 2025, most financial advisors will use web-based software to create and manage Custom Indexes for their clients. Standard indexes have a single methodology; one ruleset dictating what they own and how they rebalance. Standard indexes are “one size fits all.” Like standard indexes, Custom Indexes also invest and rebalance according to a defined methodology.
Direct-reading instruments for aerosols: A review for occupational health and safety professionals part 2: Applications
Abstract Direct reading instruments (DRIs) for aerosols have been used in industrial hygiene practice for many years, but their potential has not been fully realized by many occupational health and safety professionals. Although some DRIs quantify other metrics, this article will primarily focus on DRIs that measure aerosol number, size, or mass.
Direct-reading instruments for aerosols: A review for occupational health and safety professionals part 1: Instruments and good practices
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Review and demonstration of equations applied to models of filtering facepiece respirator particle capture efficiency
Abstract The use of filtering facepiece respirators (FFRs) of various types increased dramatically by both workers and the public during the ongoing COVID-19 pandemic. This increased use has, likewise, instigated a proliferation of research on the qualities of FFRs. An aspect of FFR development and optimization involves the use of mathematical models that predict filter efficiency based on various filter characteristics while also considering a number of particle capture forces.
Particle-phase collection efficiency of the OVS and IFV Pro personal pesticide samplers
Abstract The inhalable aerosol sampling criterion has been developed to characterize the efficiency of particles entering the nose and/or mouth. However, pesticides can exist in the air in both vapor and particulate phases, which complicates exposure assessments.
A Letter to Clients From Patrick O’Shaughnessy, O’Shaughnessy Asset Management CEO
By Patrick O’Shaughnessy September 2021 Today, I have exciting news to share: O’Shaughnessy Asset Management has agreed to be acquired by Franklin Templeton, a $1.5 trillion global investment management firm with a 70-year history. It’s hard to express how excited our team is about this opportunity. We believe Franklin Templeton is going to be an outstanding partner for our clients and for our team. This news is the culmination of extensive talks between our two firms to ensure a proper fit.
Republicans' presidential ambitions should rest on more widely popular policies, not the electoral college
This is in response to the recent opinion piece by Dennis Clayson on the need to retain the electoral college ("Electoral College unfair to all voters, rural and urban, Republican and Democrat alike"). He uses the example of Nevada ranchers who (presumably by voting for a Republican president) are “disenfranchised and have been removed from the democratic process” by a huge voting block of urbanites from Las Vegas (who are presumably Democrats).
Custom Indexing: The Next Evolution of Index Investing
By Patrick O’Shaughnessy December 2020 By 2025, most financial advisors will use web-based software to create and manage Custom Indexes for their clients. Standard indexes have a single methodology; one ruleset dictating what they own and how they rebalance. Standard indexes are “one size fits all.” Like standard indexes, Custom Indexes also invest and rebalance according to a defined methodology.
Microcap as an Alternative to Private Equity
By Chris Meredith, Patrick O’Shaughnessy December 2017 Private equity (PE) has become a central component of many institutional and high-net-worth investment portfolios over the past decade. While private equity offers potential advantages, it also requires taking distinct risks. This paper highlights an alternative to private equity—microcap equities—which mitigates several of these risks. Institutional investors have changed their asset allocation over the past 18 years.
An Update From OSAM
By Patrick O’Shaughnessy March 2020 March 10, 2020 OSAM clients, Like everyone we are watching markets and the coronavirus carefully and thinking of ways to be safe and helpful. In acutely painful markets, we have two goals. First, to execute our firm’s strategies as flawlessly as we can with a clear emphasis on trading and portfolio management, risk management and rebalancing, and client communication.
O'Shaughnessy Quarterly Letter Q4 2019
By Patrick O’Shaughnessy January 2020 Download PDF O’Shaughnessy Quarterly Investor Letter Q4 2019 January 8, 2020 Dear Investor, In 2019, we completed more research than in any prior year, built and launched CanvasTM, and shared 13 papers and over 50 podcasts. We grew our team and operated with more focus than in any year I can remember. As of the end of the year, we are managing $5.7B in assets under management, across 2,508 accounts for individual and institutional investors.
O’Shaughnessy Quarterly Investor Letter Q3 2019
By Patrick W. O’Shaughnessy, Chief Executive Officer and Portfolio Manager October 2019 Download PDF Dear Investor, Between ongoing research projects and our rollout of the new Canvas platform, we’ve had a very busy quarter at OSAM. In this letter I’ll begin by highlighting the most interesting trend we see inside equity markets today, and finish by sharing the five key lessons that we’ve learned so far after demoing Canvas for more than 100 advisors and other capital allocators.
Executive Summary - The Earnings Mirage: Why Corporate Profits are Overstated and What It Means for Investors
By Patrick W. O’Shaughnessy, Chief Executive Officer and Portfolio Manager July 2019 Download PDF This is a summary of findings from a recent long-form research piece by Jesse Livermore+, "The Earnings Mirage". The conceptual problems with book value as an accounting tool are well-known. But one problem that often gets missed is the problem of inflation. Book values are not adjusted for inflation over time, and therefore they tend to understate the true value of corporate net assets.
O’Shaughnessy Quarterly Investor Letter Q1 2019
By Patrick W. O’Shaughnessy, Chief Executive Officer and Portfolio Manager March 2019 Download PDF Dear Investor, While there have been some lone geniuses in investing, able to single-handedly choose investments which lead to extraordinary returns, they are few and far between. Real investing edge should instead be cultivated at the organizational level. Properly built, an edge should be very difficult or impossible for others to replicate.
Alpha within Factors
In Factors from Scratch, we showed that value investing works through a re-rating process.
O'Shaughnessy Quarterly Investor Letter Q3 2018
Basic factor investing is settled territory. Most investors have been bludgeoned with countless strategies that use factors like value, momentum, quality, or low volatility. As William Gibson observed in Pattern Recognition, “commodification will soon follow identification.” The primary factors were identified long ago and have been packaged and repackaged in just about every way imaginable.
O’Shaughnessy Quarterly Investor Letter Q3 2018
Basic factor investing is settled territory. Most investors have been bludgeoned with countless strategies that use factors like value, momentum, quality, or low volatility. As William Gibson observed in Pattern Recognition, “commodification will soon follow identification.” The primary factors were identified long ago and have been packaged and repackaged in just about every way imaginable.
O’Shaughnessy Quarterly Investor Letter Q4 2018
By Patrick W. O’Shaughnessy, Chief Executive Officer and Portfolio Manager January 2019 Download PDF Dear Investor, In this letter, I address the most common questions that we field at OSAM by discussing: I. 2018 performance II. Whether the market looks attractive as of January 2019 III. Factor performance during 2018 (which started fine and ended very badly) IV. Our vision for the long-term future of OSAM.
O’Shaughnessy Quarterly Investor Letter Q2 2018
In this quarter's letter, we're going to share our thoughts on three key topics: the Value factor’s extended run of poor performance, the ways we believe asset managers can borrow concepts from the technology sector, and our current research agenda. Is Value ever going to work again?
Factors from Scratch | O'Shaughnessy Asset Management
With a million dollars to invest today, would you rather buy a portfolio of New York City taxi medallions or shares in Uber stock? When we ask investing audiences this question, the answer is almost always Uber. People tend to think in terms of fundamental growth without also thinking about price. In terms of growth and excitement, Uber has the clear edge.
Cycling deaths are serious concern.
There has been a lot of news concerning bicycling lately. Of course, the Register's Annual Great Bicycle Ride Across Iowa has wrapped up, with all its associated hype in the press. We have also heard of efforts by the Iowa Bicycle Coalition to enforce a car-passing law. In April, the Register printed a sobering article on the 22 bicycle deaths in Iowa due to collisions with other vehicles.
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