Have you ever thought that if you were born in February, you have more probabilities of becoming a professional Hockey player, than if you were born in December? Let's analyze more about this and other sports.

Matthew 25:29 in the bible explains that “whoever has will be given more, and they will have an abundance. Whoever does not have, even what they have will be taken from them” which has lead many researchers to describe how some get more and others get less as the Matthew effect in our society.

One way to evaluate this effect is to look at professional athletes. Malcolm Gladwell studies the birth dates of successful hockey players in a chapter of his 2008 non-fiction book Outliers to provide an example of the Matthew Effect.

Hockey’s cutoff date is December 31st, but baseball’s cutoff date has historically been July 31st. Football’s cutoff is July 31st too, but they also have weight categories as well for older ages. Basketball’s Amateur Athletic Union (AAU) cutoff date is August 31st.

Malcolm Gladwell’s chapter on the Matthew Effect is persuasive as a narrative. He even has a couple of tables. After reading his Matthew Effect chapter, your job is to create a few persuasive visualizations about the birthday distributions within each sport. In addition, you will need to compare the sport birthday distributions to the distribution of birthdays in the US population to verify that the two groups are in fact different.

Group A: baseball players born in June-August.
Group B: US people born in June-August.
P-Value is greater than 0.05, so it is a great chance of becoming a baseball player if you were born in any of these months.

Group A: baseball players born in September-November.
Group B: US people born in September-November.
P-Value is lower than 0.05, so it is a small chance of becoming a baseball player if you were born in any of these months.

Each sport has a cutoff date, this can be an advantage to many aspirants.
Hockey - December, 31
Baseball - July, 31
Football - July, 31
Basketball - August, 31

We can use hockey as reference: most of the players were born in the first 3 months of the year and, from August there's an interesting decline in the amount of players.

These are the months with the lowest probability of becoming a professional player.
Using the probability of baseball, 1/10874, only around 6 persons out of each 1957 persons born in June will make it.

These are the months with the highest probability of becoming a professional player.
Using the probability of baseball, 1/7844, only around 4 persons out of each 1957 persons born in August will make it.

As mentioned in the previous slides, the month you born can affect your probabilities of becoming a professional player, of course it depends on different factors, but as in baseball, despite of having lower probability of becoming a professional, more people who were born in June make it, compared than those who were born in August, with a higher probability, less people make it.
Matthew effect was also demonstrated for hockey players, there's a higher probability of becoming a professional if you were born in February than if you were born in December, since the cutoff date is December, 31, so the earliest of the year you were born, the earliest you can prepare to play hockey.