Progress Daily

Since 1948 three generations of residents in Framingham have participated in regular medical examinations. A new study (”Alone in the crowd: The structure and spread of loneliness in a large social network”; .pdf file here) by John Cacioppo that uses Framingham to analyse loneliness has found that it spreads very much like a communicable disease.

Participants in the study were routinely asked to list people who would probably know their whereabouts in the next 2 to 4 years, & were asked to describe their relationship with each person as friend, spouse, sibling, neighbour or colleague. Between 1983 and 2001 participants were regularly asked to state how many days a week they felt certain feelings, such as loneliness.

Analyzing this data, the researchers found that loneliness formed in clusters of people, and that once one person in a social network started expressing feelings of loneliness, others within the same network would start to feel the same way. Those who had immediate contact with lonely people were around 50% more likely than average to feel lonely themselves. In people who knew people who had direct contact with lonely people, the figure was 25%. Those with three degrees of separation showed roughly a 10% increase.

The effects were more noticeable among friends than family, and stronger among women than men.

“Alone in the crowd,” The Economist

The fertility rate of half the world is now 2.1 or less — “the replacement rate of fertility” (the number that is consistent with a stable population). If current trends continue, sometime between 2020 and 2050 the world’s fertility rate will fall below the global replacement rate.

Mothers in developing countries today can expect to have three children. Their mothers had six.

“Falling fertility,” The Economist

Richard Tol collected data on climate and conflict in Europe over the past thousand years (”Climate Change and Violent Conflict in Europe over the Last Millennium“).

Until the mid-18th century, the correlation between the number of conflicts and the average temperature is continuously and significantly negative — lower temperatures mean more wars. The line remains close to the 95% confidence level, suggesting there is only one chance in 20 that it is an accidental, random effect. Then, suddenly, the negative correlation vanishes. (The line goes into positive territory, but not enough to be statistically meaningful.)

The researchers suggest that in the more remote past the effects of cold weather on harvests led to supply shortages, and that these increased the likelihood of people fighting over food and the land needed to produce it. They argue that the reason the relationship between warfare and cold vanishes in the mid-18th century is that this is the moment when the industrial revolution began. The food supply increased and improvements in transportationallowed food to be more easily shipped to areas of scarcity.

Farmers could more often produce reasonable yields during colder weather — and long-distance trade provided a buffer against crop failure.

“Cool heads or heated conflicts?,” The Economist

According to Andrew Smithers‘ two favourite stock market valuation measures, the q ratio (which compares share prices with the replacement cost of net assets) and the cyclically adjusted price/earnings ratio (which averages profits over ten years), the US market is still overvalued. According to these measures, Wall Street fell to merely average, not low, valuations in the recent crash.

“The end is nigh (again),” The Economist

Research by Emma Cohen (”Rowers’ high: behavioural synchrony is correlated with elevated pain thresholds“), suggests that training in a synchronised group may heighten tolerance for pain, & allow people to train longer.

The researchers got 12 members of Oxford’s heavyweight squad to row on machines in four 45-minute sessions over two weeks. In two sessions they rowed in complete isolation and in the others in groups of six, perfectly synchronised. Immediately following each session they deduced pain tolerance by gradually tightening a cuff around each rower’s arm. When he said “now” they stopped squeezing and noted the pressure.

The rowers’ pain thresholds were significantly higher following the group sessions. This was despite nearly identical power outputs in all four tests and efforts to control for possible confounding variables, such as the time of day.

“Fitter with friends,” The Economist

Girls who grow up without their fathers at home reach sexual maturity earlier than girls whose fathers live with them (and early-bloomers are more likely to suffer depression, hate their bodies, engage in risky sex and get pregnant in their teen years).

Research by Jane Mendle (”Associations Between Father Absence and Age of First Sexual Intercourse“) suggests heredity is the cause: the genes that make a dad more likely to leave his family also cause early sexual development.

The researchers analyzed data American National Longitudinal Survey of Youth data on 1,400 boys and girls, each of whom was related to at least one other subject through their mother. Most of the mothers were pairs of sisters, but some were identical twins or first cousins raised as sisters.

The more closely related the cousins were — by having mothers who were identical twins, for instance, versus cousins — the closer their age at first sexual experience, regardless of whether or not a father lived in the home.

“Daddy’s girl,” The Economist

The evidence suggests that as the number of cyclists in a city increases, the level of safety-per-cyclist increases so quickly that more bike riders leads to fewer bike accidents.

“Safety in Numbers: It’s Happening in NYC,” by Ben Fried

“Safety in Numbers,” by Matthew Yglesias

[I]t does not make sense to talk about market efficiency without taking into account that market participants have bounded resources. In other words, instead of saying that a market is “efficient” we should say, borrowing from theoretical computer science, that a market is efficient with respect to resources S, e.g., time, memory, etc., if no strategy using resources S can generate a substantial profit. Similarly, we cannot say that investors act optimally given all the available information, but rather they act optimally within their resources. This allows for markets to be efficient for some investors, but not for others; for example, a computationally powerful hedge fund may extract profits from a market which looks very efficient from the point of view of a day-trader who has less resources at his disposal—arguably the status quo.

“A Computational View of Market Efficiency”

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“We analyze the intertemporal stability of returns to technical trading rules in the foreign exchange market by conducting true, out-of-sample tests on previously published rules. The excess returns of the 1970s and 1980s were genuine and not just the result of data mining. But these profit opportunities had disappeared by the mid-1990s for filter and moving average (MA) rules. Returns to less-studied rules, such as channel, ARIMA, genetic programming and Markov rules, also have declined, but have probably not completely disappeared. …The most likely time for a structural break in the MA and filter rule returns is the early 1990s. These regularities are consistent with the Adaptive Markets Hypothesis (Lo, 2004), but not with the Efficient Markets Hypothesis.”

“The Adaptive Markets Hypothesis: Evidence from the Foreign Exchange Market”

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“Have You Reviewed Papers on the Adaptive Market Hypothesis?,” CXO Blog

The cost of sequencing DNA has fallen from about $1 per base pair in the mid-1990s to a tenth of a cent today. Rob Carlson started tracking the price of DNA synthesis a decade ago. He found a steady decline, from over $10 per base pair to, lately, well under $1. This decline recalls Moore’s law, which, when promulgated in 1965, predicted the exponential rise of computing power.

A study by Amir Barnea, Henrik Cronqvist and Stephan Siegel (”Nature or Nurture: What Determines Investor Behavior?“), based on characteristics for approximately 40,000 identical and non-identical twins from the Swedish Twin Registry and associated investing data for the period 1998-2006, concludes that genetics explain up to 45% of individual variation in stock market participation, asset allocation and portfolio risk choices.

Genetic influence is robust to differences in age, education and net worth. Genetics explain more of the variation in individual investing behavior than does an extensive set of individual characteristics combined.

Family environment has an effect on the investing behavior of younger individuals, but this effect disappears as they acquire non-family experiences.

“The Genetics of Investing (Not the Algorithms),” CXO