Five fatal incidents on Friday, March 13

We all had our own superstitions throughout our childhood.

Sometimes it was a particular pair of pajamas that you were convinced would give you a snow day the next morning, or maybe it was a Sergei Fedorov jersey that you refused to wash because you wore it during all of the Stanley Cup playoff games in the 1997-98 season. Maybe you washed that jersey at some point in the last few years. Maybe you shouldn't have.

According to the Stress Management Center and Phobia Institute, fear of Friday the 13th affects up to 21 million people in the United States, making it the most feared day in history. It is estimated that up to $900 million is lost on this day because citizens are too afraid to go out and engage.

Why do people fear this date? It's unclear how this date became such a notoriously unlucky day. However, it is generally believed that in many cultures the number 12 is a lucky or full number and that going beyond 12 and reaching 13 is going too far. There are 12 months in a year, 12 signs of the zodiac, 12 tribes of Israel, Jesus had 12 disciples, 12 imams, 12 gods of Olympus, a dozen doughnuts, the human body has 12 cranial nerves, an octave has 12 pitches, 12 people have landed on the moon, 12 Angry Men is a great movie – and still relevant 60 years later.

Costa Concordia

The Costa Concordia was a cruise ship that served for seven years until its fatal shipwreck on Friday, January 13, 2012.

The cruise ship was on the first leg of a cruise in the Mediterranean when it struck a rock formation after deviating from its planned course. Two years after the shipwreck, over 30 people died, including 32 passengers and a salvage worker. Since then, new safety regulations have been issued at the federal and international level, as well as by Costa Concordia's parent company, to prevent accidents.

Siachen conflict

The Siachen Glacier lies between India and Pakistan, with both countries laying claim to the region. After nearly 40 years of tough negotiations, the conflict reached its peak on Friday, April 13, 1984, sparking a war that technically still continues 36 years later.

More than 2,000 people were killed on the highest battlefield on earth, 20,000 feet above sea level. It is estimated that 97 percent of the casualties were not due to actual fighting, but to weather, avalanches and lack of oxygen.

Although a ceasefire came into effect in 2003, the two countries have 150 outposts on the glacier, including the world's highest telephone booth and helipad. The lower air pressure at high altitudes has prompted India to develop a modern helicopter suitable for the task.

Kitty Genovese

The murder of Kitty Genovese has been a staple of ethics and psychology lectures for over 50 years.

She was born and raised in Brooklyn, and stayed in the city even after her parents moved to Connecticut and her mother witnessed a murder on the streets of New York.

On Friday, March 13, 1964, Genovese was followed home from work and stabbed to death outside her apartment complex. Her cries for help were allegedly ignored by the complex's residents, who failed to see the fatal attack, leading to the bystander effect, a social phenomenon in which people are less willing to help in times of need when others are present. This phenomenon is taught in nearly every psychology course in the country.

The truth behind the real murder is a little different from the sensationalist version that has become popular in popular culture. While no one doubts that the murder actually happened, the details behind the conspicuousness of the attack and the apathy of witnesses in New York City are believed to be less than accurate. The New York Times, whose cover story on the case captured media attention in 1964, recently called its original article “flawed,” “grossly exaggerated,” and that the inaccurate reports had “taken on a life of their own.”

It is believed that the bystander effect can be avoided in times of crisis by singling out a single person and explicitly demanding that he or she be helped.

Tupac Shakur

On September 7, 1996, influential hip-hop artist Tupac Shakur was shot four times in a drive-by shooting in Las Vegas. The attack was believed to be a response to a fight Shakur had been involved in earlier that evening.

One of the bullets pierced Shakur's right lung, and Shakur was placed on life support in the hospital and later placed in an induced coma. He eventually died of respiratory failure on Friday, September 13, after his damaged lung was surgically removed.

Attacks in Paris in November 2015

The deadliest attack on French soil since World War II was a series of coordinated terrorist attacks across the city of Paris and its suburb of Saint-Denis on Friday, November 13, 2015.

While several groups claimed responsibility for the attacks, then-French President François Hollande said ISIS was to blame. The attack's organizer was killed in a raid four days later. Muslim leaders around the world condemned the attacks, and new security regulations were enacted worldwide in the hope of preventing future attacks.

Is Friday the 13th actually an unlucky day?

Research and statistics have failed to show that bad situations are more likely to occur on Friday the 13th, and that the human tendency to favor or interpret information in a way that confirms what one already believes to be true (commonly known as confirmation bias) is to blame. Although many bad incidents have happened on this superstitious day, we find it easier to view them as connected and disregard the amount of bad events that happen on literally every other day of the year.

Some good things happened on this day, too. President Lyndon B. Johnson signed Executive Order 11375, banning sex discrimination in public employment, on Friday, October 13, 1967. Nintendo released the highly successful Super Mario Bros. video game for the NES on Friday, September 13, 1985, popularizing one of the most recognizable characters in the media. Black Sabbath's influential eponymous debut album, widely considered the first in the metal genre, was released on Friday, February 13, 1970. Several people won lottery drawings on this unlucky day.

Was this really an unlucky day? Given the amount of data and history available on this day, it is difficult to say for sure. Nor are we claiming that the good things that happened outweigh the atrocities that occurred.

Stay safe. If you are concerned, be careful not to walk under ladders, avoid black cats and Please Leave the Fedorov jersey unwashed this year.