The term bell curve comes from the shape of the curve, which is a bit like a bell.
We will soon make a connection between normal distribution and professional Dota 2.
Each of the shaded regions indicate the number of standard deviations.
Standard deviation () is a measure of how spread out numbers are in a dataset.
So three standard deviations are typically enough to include nearly all the data.
That is what most normal distributions will show.
The normal distribution curve is popular because there are many examples in life which fall in a similar pattern.
The question in our case is do Dota 2 games follow the same trend?
The average for this dataset is 37 minutes 24 seconds with a standard deviation of 10 minutes 45 seconds.
The question now is, how far is the data from achieving a normal distribution curve?
If that skewness is more than 1 (calculations for which can be found in a statistics book!
), the data is said to be highly asymmetric and not approximated very well by a normal distribution.
Kurtosis sheds light on how spread out or concentrated a set of data is.
A normal distribution has a kurtosis value of 3.
Higher than that means the data is more concentrated around the average game duration.
In Dota 2 terms, it would mean the majority of the games fall very close to the average.
Now that we have learned these statistical terms, it is time to put them to good use.
The numbers reveal some fascinating stuff.
The number of games, average game length and standard deviation of game lengths were obtained fromdatDota.
But for it to fall into such a small window is no small feat.
IceFrog and Valve have found the right knobs to turn to make the long-term data fall into that window.
Skewness The skewness is positive for all groups, which is not a surprise as discussed previously.
All of them, though, are above 1, which shows a significant deviation from a normal distribution.
As it turns out, Dota 2 games do not closely match a bell curve.
What is the overarching takeaway from this statistics class?
The first one is that mathematics can be fun when applied to something interesting like Dota 2!
But in terms of professional games, the data cannot be mimicked by a normal distribution.
