Popular Personal Financial Advice versus the Professors (James Choi, NBER)

Link post

This econ paper about personal finance was featured in a recent Freakonomics Radio episode. It compares the financial advice in popular personal finance books with what economics research says is optimal financial behavior.

Some of the most surprising (to me) recommendations in the paper:

  • It’s actually suboptimal to put away a fixed percentage of your income as savings every year. Instead of smoothing your savings, you should smooth your consumption so that you spend the same amount of money every year. Since most people’s earnings potential peaks in midlife, it’s best to have a small or even negative savings rate early in your career, and save the largest percentage of your income toward the midpoint of your career.

    • Smoothing consumption over time makes sense to me. If you know that you will be able to earn a fixed amount of money over your lifetime, then you ought to spend it evenly over time, as this maximizes your utility at each point in time given diminishing marginal utility of spending.

    • However, consumption smoothing implies a different optimal strategy for those interested in jumping from a high-paying career to a less highly paying one such as entrepreneurship, nonprofit work, or the arts. In general, your savings rate should be highest when your earnings potential is highest. But if you expect to earn the most early in your career, then that’s when your savings rate should be the highest. For these people, saving a fixed % of your income is probably closer to the right move.

  • Many popular finance books recommend overweighting U.S. stocks relative to the international stock market, since U.S.-based multinational companies provide exposure to international markets and international stocks carry a number of risks such as currency risk and weaker accounting and financial transparency standards. However, most economists reject arguments for overweighting the U.S. market, recommending instead that “every investor should hold each country’s securities in proportion to its market capitalization” (p. 16).

    • First, the costs and perceived risks of exposure to international stocks are too small to justify the amount of home bias that we see among investors.

    • Second, “the correlation of multinationals’ stock returns with their domestic stock market is very high, limiting the international diversification benefit obtained by buying the multinational stocks of one’s own country” (p. 17).

    • Third, any perceived strengths and weaknesses of each country’s stock market would be factored into the prices of their stocks.

  • Adjustable-rate mortgages (ARMs) are generally preferable to fixed-rate mortgages (FRMs) except when interest rates are at historical lows. This is because FRMs are exposed to inflation risk whereas ARMs are not; ARM interest payments tend to fluctuate 1-to-1 with inflation rates. Also, “ARMs usually charge lower interest rates than FRMs because ARM interest rates are pegged to short-term interest rates, whereas FRM interest rates are pegged to long-term interest rates and include a premium for offering the refinancing option” (p. 20).

Pop personal finance advice is probably logistically and emotionally easier for the average person to implement than the recommendations of the econ literature, except for relatively simple ones like “don’t overweight the U.S. market”. For example, following a rule of thumb like saving 10% of your income every year is easier on the brain than figuring out how to smooth your consumption based on your current and projected future earnings. Morgan Housel, the personal finance writer who was interviewed for the Freakonomics episode, repeatedly stresses that, unlike the econ literature, the advice of popular finance books accounts for the fallibility of the human mind. However, if you’re like me, you probably get peace of mind by doing the economically optimal thing, even if it’s trickier. For those of us who value optimal personal finance strategy, following the recommendations of the econ literature might be worth the challenge.

In my opinion, a major reason why many people are not following the advice of economists is that economists don’t spend enough time promoting the views of the field to the general public. This is true in the realm of public policy, where simplistic talking points crowd out expert opinion on many issues, but it’s also true in personal finance. Personally, I was not even aware that the econ literature had many recommendations for personal finance other than the widely-publicized “invest in low-cost index funds”. Even one personal finance podcast based on the results in the econ literature, simplified into heuristics that any person can follow, could help many people improve their finances.

Crossposted to EA Forum (39 points, 6 comments)