Can you pick out the random set of points in a plane?

Click For Summary

Discussion Overview

The discussion revolves around the concept of randomness in the placement of points in a plane, specifically addressing the criteria that define a set of points as "random." Participants explore the implications of independence and uniform distribution of random variables, as well as the perception of randomness in various contexts, including sports statistics.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that the right set of points is random, while others argue that the left set, despite appearing even, can also be considered random by certain measures.
  • There is a distinction made between points that are independent and uniformly distributed versus those that may have dependencies based on prior points.
  • One participant notes that clustering in random independent events is often underestimated, leading to misconceptions about randomness.
  • Another participant draws an analogy with baseball hitting streaks, suggesting that both random and non-random factors can contribute to perceived performance peaks.
  • A later reply discusses the concept of accident blackspots, highlighting how random clustering can lead to misinterpretations in statistical definitions.

Areas of Agreement / Disagreement

Participants express differing views on the definition of randomness and the implications of clustering in random events. There is no consensus on whether the left or right set of points is more accurately described as random, and the discussion remains unresolved regarding the interpretation of randomness in various contexts.

Contextual Notes

Participants acknowledge the complexity of defining randomness, particularly in relation to independence and the effects of prior events on subsequent outcomes. The discussion highlights the potential for misinterpretation in statistical definitions and the influence of clustering on perceived randomness.

Spinnor
Gold Member
Messages
2,231
Reaction score
419
TL;DR
Can you pick out the random set of points in a plane?
1565266133095.png


The above screen shot is from, @ the 1:43 mark. Which set of points is random? Answer below.
The right set of points.
 
Physics news on Phys.org
Did that surprise you? The one on the left is far too even to be "random".

Of course, I am assuming that by "random" you mean that each point is placed at a location (X,Y) where X and Y are independent random variables each with a uniform distribution. You could have random X, Y that are not independent but are nevertheless random or you could have random X, Y that are not uniformly distributed.
 
  • Like
Likes   Reactions: FactChecker
Dale said:
Did that surprise you?

I stopped the video to think about the pictures. I guessed right. The picture on the left is by some measure random as explained in the video. The answer might not be obvious to everyone. Thought some here might enjoy it.
 
  • Like
Likes   Reactions: Dale
Spinnor said:
The picture on the left is by some measure random as explained in the video.
I disagree. The video is using the term "random" to mean "random and independent of each other". As the video says, those points start out random, but then criteria are applied based on the prior dots to determine if each new dot will be included or not. So the dots are not independent of each other.
The answer might not be obvious to everyone.
It certainly is not. There is more clustering in random independent events than people expect in general. When they see a random cluster, they very often think that something non-random is going on. For instance, a baseball batter on a hitting streak is often thought to be better in general. But it might just be the clustering of random hits.
Thought some here might enjoy it.
I think that it illustrates a good point.
 
  • Like
Likes   Reactions: Dale
FactChecker said:
For instance, a baseball batter on a hitting streak is often thought to be better in general.

As far as hitting baseballs I am pretty sure that in addition to some randomness and fluctuations in the pitcher's pitches, a batter can peak both physically and mentally and be better able to hit a homer so a streak of home runs can be the result of both random and non random conditions? Same goes for the pitcher, his abilities can peak and make it harder for the home run hitter?
 
Spinnor said:
As far as hitting baseballs I am pretty sure that in addition to some randomness and fluctuations in the pitcher's pitches, a batter can peak both physically and mentally and be better able to hit a homer so a streak of home runs can be the result of both random and non random conditions? Same goes for the pitcher, his abilities can peak and make it harder for the home run hitter?
Sure. That is why I said that the hot streak might just be a random cluster of hits. But, IMHO, people tend to underestimate the amount of clustering in independent random events. Therefore, they tend to attribute a hot streak to physical and mental ability more often than they should.
 
  • Like
Likes   Reactions: StoneTemplePython
FactChecker said:
But, IMHO, people tend to underestimate the amount of clustering in independent random events.
There was an article I read years ago, in the Royal Statistical Society magazine I think, talking about accident blackspots. They were defined as places on the roads where more than five accidents had happened in the preceding year, and are marked as dangerous by road signage. Fine. But they've kept the definition, so any time a place has more than five accidents in a year it gets classified as an accident black spot. The article was pointing out that everywhere will eventually have five accidents in a year just by bad luck. Apparently this kind of clustering-by-chance escaped whoever framed the definition.
 
  • Like
Likes   Reactions: 256bits, FactChecker and Dale

Similar threads

  • · Replies 15 ·
Replies
15
Views
4K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
Replies
15
Views
2K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 13 ·
Replies
13
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 3 ·
Replies
3
Views
457
  • · Replies 97 ·
4
Replies
97
Views
14K