Questions tagged [paradox]

A paradox is a statement or proposition that seems self-contradictory or absurd but in reality expresses a possible truth.

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4
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3answers
102 views

Probabilities in the Raven paradox

The raven paradox is roughly: "The statement All ravens are black is logically equivalent to All non-black entities are not ravens. Whenever we observe a non-black non-raven, the probability for the ...
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2answers
140 views

Did Jaynes ever comment on Lindley’s paradox?

I wondered whether ET Jaynes ever wrote or expressed an opinion about Lindley’s famous statistical paradox? I would be curious about his take on it, and imagine he must have done since he wrote ...
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Twist to 3 prisoners problem applying Bayes rule

T, J and B work for a company but the chairman has decided to fire one person randomly chosen through 3 cards. The chairman decides to fire with unequal probabilities -- T with probability of 15%, B ...
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1answer
48 views

Berkson's Paradox: How does pregnancy affect time for AIDS to emerge from women with HIV? [closed]

I don't understand how the following [I reworded the original] instances Berkson's Paradox; and can be analogized to the University Admissions example, where $\color{limegreen}{\text{corr(SAT, GPA)}&...
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How to program a Monte Carlo simulation of Bertrand's box paradox?

The following problem has been posted on Mensa International Facebook Page: $\quad\quad\quad\quad\quad\quad\quad\quad$ The post itself received 1000+ comments but I won't go into details about the ...
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1answer
62 views

What is the name of the statistical paradox / law that says optimizing the metric may not lead to optimal outcome

I am trying remember to the name of the statistical paradox / law name that effectively says that optimizing the metric may not lead to the optimal outcome. As far as I can recall, this paradox / law ...
121
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21answers
24k views

At each step of a limiting infinite process, put 10 balls in an urn and remove one at random. How many balls are left?

The question (slightly modified) goes as follows and if you have never encountered it before you can check it in example 6a, chapter 2, of Sheldon Ross' A First Course in Probability: Suppose that ...
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2answers
396 views

False positive paradox, the definition of “accuracy”

I have a question about the false positive paradox. It is an example that is often used to motivate Baye's formula. I first give an explanation of the paradox. Suppose there is a device which is 90 ...
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Which model is better based on test and training accuracy

I have this assignment question: You are given a dataset for cancer detection having two classes (binary classification). 0 stands for “cancer not detected” and 1 for “cancer detected”. This ...
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2answers
276 views

T-test paradox: can adding a single point very far from the null value change the outcome from significant to nonsignificant?

Let's suppose we have the situation presented in picture $1$. We have a set of $n \in \mathbb{N}$ points that have a mean larger than null hypothesis: $\bar{x}>x_{H_0}$. Also $var(x)$ is such that ...
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6answers
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Average value paradox - What is this called?

I have a dataset. Say $10$ observations and $3$ variables: ...
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3answers
376 views

Paradox of Poisson process with at least one event in the interval

Let $X_T$ is a number of events in Poisson process of unitary rate ($\lambda = 1$) within interval of length $T$. It is known that at least one event has been observed in the interval, I want to find ...
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146 views

Real world examples of the sleeping beauty paradox

The Sleeping Beauty problem is a thought experiment concerning a participant, Sleeping Beauty, who is woken once or twice based on the flip of coin and is asked her degree of belief on the coin having ...
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What's wrong with this proposed resolution to the St Petersburg Paradox?

We have a game where your payout is $2^k$ where $k$ is the number of times you flipped a coin to land on heads (if your first flip is a head, then $k=1$). Then the expected payout is: $$E = \frac{1}{2}...
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2answers
207 views

How can A and B have equal chances to be visited last if A has higher chances to be visited before B?

The classical problem considered by Ross is a random particle visiting all chairs under a circular table. That is, there is a circular buffer of size m+1, were ...
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3answers
574 views

What is the name of this statistical paradox/phenomenon: statistical significance depends on what would have happened but did not

I don't remember it exactly, and I'd like to read up on it again. It is about experiment design and frequentist hypothesis testing. A sequence of N measurements are made, and then when evaluating the ...
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Blackwell's bet

I have read about Blackwell's bet paradox on Futility closet. Here is the summary: you are presented with two envelopes, $E_x$ and $E_y$. The envelopes contain a random amount of money, but you don't ...
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1answer
64 views

What Are Some Historical Applied Stats Problems [closed]

What are some interesting, historical applied statistics problems ? i.e. sometime in the past that statistics have been used to affect the course of events? The kind of problems I am looking for ...
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0answers
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What basis should be used to devize a significance/hypothesis test?

I am trying to understand the basis of hypothesis testing and I came up with a paradox. Let me explain with an example. Consider the case of trying to determine whether is coin is fair. The null ...
3
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1answer
87 views

Probability to be the millionth customer (What Would You Do?)

I saw this episode of "What Would You Do?" a few months ago, and I keep wondering what would statistically be the best thing to do in this situation. Here is the problem formulation: You are waiting ...
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1answer
350 views

Does Stein's Paradox still hold when using the $l_1$ norm instead of the $l_2$ norm?

Stein's Paradox shows that when three or more parameters are estimated simultaneously, there exist combined estimators more accurate on average (that is, having lower expected mean squared error) than ...
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1answer
649 views

Simulating the waiting paradox

After seeing this question, I thought I would try to simulate the bus waiting time paradox to help my understanding. However, what I got was the "intuitive" result, rather than that predicted by the ...
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5answers
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Please explain the waiting paradox

A few years ago I designed a radiation detector that works by measuring the interval between events rather than counting them. My assumption was, that when measuring non-contiguous samples, on ...
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0answers
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Simpson's Paradox with new sample

Suppose you constructing model whose training data is cumulative in nature; meaning each year you can add new observations with all prior observations being kept the same. (e.g. training set is non-...
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2answers
354 views

Unkown 6-sided dice. After 600 rolls frequency for all sides exactly equal. What is the chance, that rolling “6” with this dice has frequency > 1/6?

Although it is unknown dice, the symmetry of the evidence tells us, that we can treat the dice as fair, so the chance should be exactly 50%. But if we simulate it by hand, the result is less then 50%:...
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Two envelope problem revisited

I was thinking of this problem. http://en.wikipedia.org/wiki/Two_envelopes_problem I believe the solution and I think I understand it, but if I take the following approach I'm completely confused. ...
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370 views

A seeming paradox with rational agents not coming to the same conclusion given the same data

So one day after a tasty dinner full of bananas, an idea comes to your mind (you are person A) - "What if eating bananas can cure cancer?". Being a scientist at heart, you conduct a double blind study ...
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1answer
155 views

Possible Paradox: Calculating a confidence interval with within-experiment error

This is a spinoff of How to calculate the confidence interval of the mean of means? and related to When making inferences about group means, are credible Intervals sensitive to within-subject ...
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733 views

Name of the “paradox” reported by Gelman

In Andrew Gelman's book "Red State, Blue State" he analyzes the fact that rich people within particular states tend to vote more Republican than poor people, but that wealthy states tend to vote more ...
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Question about Harrington paradox

Model The firm and enforcement agency interact in more than one domain. This may arise because a single agency is responsible for enforcing more than one regulation or because it enforces the same ...
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1answer
814 views

Swapping X and Y in a regression that contains a grouping predictor?

Suppose I'm doing a linear regression and I want to investigate how the association between a predictor X and a response Y changes according to levels of a 2-level factor G. The model would look like ...
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27answers
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The Sleeping Beauty Paradox

The situation Some researchers would like to put you to sleep. Depending on the secret toss of a fair coin, they will briefly awaken you either once (Heads) or twice (Tails). After each waking, ...
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2answers
535 views

Does the principle of indifference apply to the Borel-Kolmogorov paradox?

Consider Jaynes' solution to the Bertrand paradox using the principle of indifference. Why doesn't a similar argument apply to the Borel-Kolmogorov paradox? Is there something wrong with arguing that ...
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4answers
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What will be the correct answer, if we modify the “Best statistics question ever”?

There is a popular question, called "Best statistics question ever". If you choose an answer to this question at random, what is the chance you will be correct? A) 25% B) 50% C) 60% D) 25% This ...
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1answer
590 views

Why can't we trust our intuition with probability?

If ever there was a case where this become clear is with the Monty Hall problem. Even the great Paul Erdos got fooled by this problem. My question which may be difficult to answer is what is it ...
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19answers
26k views

Most interesting statistical paradoxes

Because I find them fascinating, I'd like to hear what folks in this community find as the most interesting statistical paradox and why.