Ever since I was a graduate student in economics, I’ve been struggling with the uncomfortable observation that economic theories often don’t seem to work in practice. That goes for that most influential economic theory, the Efficient Markets Hypothesis, which holds that investors are rational decision makers and market prices fully reflect all available information, that is, the “wisdom of crowds.”
Certainly, the principles of Efficient Markets are an excellent approximation to reality during normal business environments. It is one of the most useful, powerful, and beautiful pieces of economic reasoning that economists have ever proposed. It has saved generations of portfolio managers from bad investment decisions, democratizing finance along the way through passive investment vehicles like index funds.
Then came the Financial Crisis of 2008; the “wisdom of crowds” was replaced by the “madness of mobs.” Investors reacted emotionally and instinctively in response to extreme business environments — good or bad — leading either to irrational exuberance or panic selling.
Pennsylvania, like many other states, is facing a huge unfunded pension deficit in its defined benefit plans: a $70 billion shortfall in two large plans for teachers and other state employees. Unlike most states, Pennsylvania in early June passed — with widespread bipartisan support — major legislation “to get real meaningful pension reform,” as Gov. Tom Wolf was quoted saying.
Indeed, the recent Pennsylvania law is a significant step in the right direction. However, the financial projections for the legislation show how long it takes, given the legal and political constraints, for this approach to pension reform to meaningfully reduce the burden on state budgets.
Here is the background. In 2001, Pennsylvania reported a $20 billion surplus in its two big defined benefit plans – the Public School Employees’ Retirement System and the State Employees’ Retirement System. But then state legislators boosted benefits for current state workers without increasing contributions to these plans, and even extended this giveaway to already retired public employees. In 2003, legislators compounded the state’s funding challenge by taking a “pension holiday” — decreasing pension contributions to allocate revenue to other state priorities.
These actions contributed to a giant shortfall during the global financial crisis, when the value of the state’s pension portfolios plummeted. In response, state legislators in 2010 reduced pension benefits — only for newly hired state workers — to pre-2001 levels. Nevertheless, because of growing obligations to current and retired workers, the state’s contributions to its pension plans ballooned to $6 billion in the 2018 fiscal year from $1 billion in the 2011 fiscal year.
The spread of misinformation on social media is an alarming phenomenon that scientists have yet to fully understand. While the data show that false claims are increasing online, most studies have analyzed only small samples or the spread of individual fake stories.
My colleagues Soroush Vosoughi, Deb Roy and I set out to change that. We recently analyzed the diffusion of all of the major true and false stories that spread on Twitter from its inception in 2006 to 2017. Our data included approximately 126,000 Twitter “cascades” (unbroken chains of retweets with a common, singular origin) involving stories spread by three million people more than four and a half million times.
Disturbingly, we found that false stories spread significantly more than did true ones. Our findings were published on Thursday in the journal Science.
We started by identifying thousands of true and false stories, using information from six independent fact-checking organizations, including Snopes, PolitiFact and Factcheck.org. These organizations exhibited considerable agreement — between 95 percent and 98 percent — on the truth or falsity of these stories. Read More »
Grocery stores run price promotions all the time. You see them when a particular brand of spaghetti sauce is $1 off or your favorite coffee is buy one get one free. Promotions are used for a variety of reasons from increasing traffic in stores to boosting sales of a particular brand. They are responsible for a lot of revenue, as a 2009 A.C. Nielsen study found that 42.8% of grocery store sales in the U.S. are made during promotions. This raises an important question: How much money does a retailer leave on the table by using current pricing practices as opposed to a more scientific, data-driven approach in order to determine optimal promotional prices?
The promotion planning tools currently available in the industry are mostly manual and based on “what-if” scenarios. In other words, supermarkets tend to use intuition and habit to decide when, how deep, and how often to promote products. Yet promotion pricing is very complicated. Product managers have to solve problems like whether or not to promote an item in a particular week, whether or not to promote two items together, and how to order upcoming discounts ― not to mention incorporating seasonality issues in their decision-making process.
They say timing is everything. And in sub-Saharan Africa, where roughly a third of untreated HIV infected babies die before they reach the age of one, a timely diagnosis is everything.
According to the latest UNAIDS data, 150, 000 children are infected with HIV in sub-Saharan Africa, annually. Due to the high number of children dying, diagnosing babies with HIV as early as possible is critical.
Public health officials have been grappling with this for many years. How can they reduce the time it takes to get newborns’ blood samples to the diagnostic lab and the test results back? This matters because it determines how soon babies can start medical treatment. The average turnaround time in sub-Saharan Africa often range from one to three months.
In general, shorter turnaround times can be achieved by improving the clinic-to-lab supply chain. This can happen through increasing the number of vehicles equipped to transport samples, hiring enough drivers, training enough medical personnel, buying the right type of diagnostic equipment, and improving communication systems.
African countries like Malawi and Nigeria have done this, with impressive results. Read More »