Are the dice here really random?

[Chouxflower]

I just rolled double fives, four times in a row, in a game of backgammon. Kinda weirded out a little here...

[Jest Phulin]

The probability of rolling double 5s is 1:36. Therefore, the probability of rolling 4 double 5s in a row is 1:1679616. But, I'm pretty sure this post would have been made if it were double 3s, or double 2s, or any set of 4 of the same doubles in a row. That makes the probability 6:1,679,616, or 1:279,936.
Looking at the statistics page on backgammon, it looks like the average game takes between 25 and 26 rolls. Dividing, this makes the probability about 1:11000 per game of it happening. Again from the stat page, the average player takes 7132 minutes to play the game (including turn-based and real-time). This puts the average game taking a little less than 5 days. Currently, there are 750 turn-based games happening. I'm not going to consider the real-time, as that varies throughout the day. Using 750 games with the average game being 5 days gives roughly 150 games per day. It is probably higher since I'm not considering real-time as I don't have access to those numbers. So, combining that with the 1:11000 per game of it happening, it looks like this is expected to happen about once every 74 days. Again, this is on the low end. It probably happens more often than that.

There is nothing wrong with the dice determination on this site based on this. The human mind is poor at determining what is really random. You might want to read the section on die rolls in the FAQ linked at the bottom of this page .

Also, consider that the chances of winning the most common type of lottery (pick 6 numbers from a pool of 49) is 1:13,983,816 Yet people win.

[fafa-fr]

Currently, there are 750 turn-based games happening. I'm not going to consider the real-time, as that varies throughout the day. Using 750 games with the average game being 5 days gives roughly 150 games per day. It is probably higher since I'm not considering real-time as I don't have access to those numbers.

At the moment, about 60800 real-time backgammon games were played in april (and 5500 turn-based). So in average more than 2000 per day. (In february it was almost 23000 real-time and 3500 turn-based.) So it is not surprising at all that rolling 4 doubles in a row happens several times a month on BGA. If some day it happens that dozens of 4 doubles in a row are reported in the forum in a year, this would be a sign that something may be wrong.