Chance Error and Coin Tossing

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Questions and Answers

According to Kerrich, what happens to the chance error (the difference between the number of heads and half the number of tosses) as the number of coin tosses increases?

  • It tends to decrease in absolute terms.
  • It decreases in absolute terms, but increases as a percentage of the total tosses.
  • It tends to increase in absolute terms, but decreases as a percentage of the total tosses. (correct)
  • It remains constant.

In Kerrich's coin-tossing experiment, what was the difference between the number of heads and half the number of tosses after 1,000 tosses?

  • 33
  • 2 (correct)
  • 67
  • 5

What is the significance of the phrase "the roulette wheel has neither conscience nor memory" in the context of probability and the law of averages?

  • It emphasizes that the house always wins in the long run.
  • It suggests that roulette wheels are rigged to give certain outcomes.
  • It means that each spin of the roulette wheel is independent and unaffected by previous spins. (correct)
  • It implies that past outcomes influence future probabilities in random events.

Kerrich states that after a run of four heads, the probability of getting a tail on the next toss is:

<p>Approximately 50% because coin tosses are independent events. (B)</p> Signup and view all the answers

According to Kerrich, if one multiplies the number of tosses by 100, what happens to the likely size of the chance error?

<p>It multiplies by 10. (B)</p> Signup and view all the answers

In the context of the law of averages, what does 'chance error' refer to?

<p>The unavoidable difference between the expected outcome and the actual outcome in a series of random events. (B)</p> Signup and view all the answers

Which statement about the law of averages is most accurate, according to Kerrich?

<p>The difference between the number of heads and half the number of tosses gets bigger as the number of tosses increases, but the percentage difference gets smaller. (A)</p> Signup and view all the answers

If Kerrich tossed a coin 100 times, approximately what size of chance error would he likely expect?

<p>Around 5 (D)</p> Signup and view all the answers

What was the main purpose of John Kerrich's coin-tossing experiment during World War II?

<p>To pass the time while interned in a camp and to study probability theory. (B)</p> Signup and view all the answers

What is the correct formula, according to Kerrich?

<p>Chance Error = Number of heads - Half the number of tosses (A)</p> Signup and view all the answers

What common misconception about the law of averages did Kerrich address with his assistant?

<p>That after a series of one outcome (e.g., heads), the opposite outcome (tails) becomes more likely. (C)</p> Signup and view all the answers

Based on Kerrich's findings, if someone tosses a coin 20,000 times, what can they expect regarding the chance error compared to 10,000 tosses?

<p>The chance error will be larger in absolute terms but smaller as a percentage of the total tosses. (A)</p> Signup and view all the answers

Why was Kerrich's coin-tossing experiment significant in understanding the law of averages?

<p>It illustrated that while the absolute difference between expected and actual results increases, the relative difference decreases with more trials. (B)</p> Signup and view all the answers

If a coin is tossed many times and the percentage of heads is slightly less than 50%, what does the law of averages suggest will happen as more tosses are performed?

<p>The percentage of heads will get closer to 50%, but the absolute difference between the number of heads and tails will likely increase. (C)</p> Signup and view all the answers

What is a practical implication of the law of averages in real-world scenarios?

<p>Long-term trends are more predictable, but individual events remain random. (A)</p> Signup and view all the answers

What does Kerrich mean when he says, "The number of heads will be around half the number of tosses, but it will be off by some amount—chance error."

<p>That getting exactly 50% heads is impossible. (C)</p> Signup and view all the answers

What is the role of the assistant in Kerrich's discussion?

<p>To challenge Kerrich's understanding and reveal common misconceptions about the law of averages. (B)</p> Signup and view all the answers

In the context of Kerrich's experiment, what is the key difference between the 'absolute' chance error and the 'relative' chance error?

<p>The absolute error is the actual deviation from the expected value, while the relative error is this deviation expressed as a percentage of the total number of trials. (C)</p> Signup and view all the answers

Why does Kerrich use the example of tossing a coin multiple times to explain the law of averages?

<p>Because it is a simple and easily understandable example of a random process. (B)</p> Signup and view all the answers

How does Kerrich use Table 1 and Figure 1 from his experiment to argue his point about the law of averages?

<p>By illustrating that the actual number of heads deviates from the expected number, and that this deviation tends to grow in absolute size, though it shrinks relatively. (C)</p> Signup and view all the answers

Flashcards

Chance of Heads

With a fair coin, the chance of getting heads remains at 50%, regardless of previous outcomes.

Chance Error

The difference between the observed number of heads and the expected number (half the number of tosses).

Chance Error Increase (Absolute)

As the number of trials increases, the absolute size of the chance error tends to increase as well.

Chance Error Decrease (Relative)

As the number of trials increases, the chance error becomes smaller when expressed as a percentage of the total number of trials.

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Law of Averages Definition

The number of heads will be approximately half the number of tosses, with some amount of chance error.

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Chance Error Size

Describes the likely magnitude of the chance error in relation to the number of tosses.

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Chance Error Scaling

Increasing the number of tosses by a factor of 100 only increases the likely size of the chance error by a factor of 10.

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Study Notes

  • The law of averages is commonly misunderstood to mean that after a series of heads in coin tosses, tails become more likely to even out the results.
  • The chance of getting heads with a fair coin remains at 50%, regardless of previous outcomes.

Kerrich's Coin-Tossing Experiment

  • John Kerrich, while interned during World War II, conducted an experiment involving 10,000 coin tosses.
  • In 10,000 tosses, Kerrich got 5,067 heads, a difference of 67 from the expected 5,000.
  • The "chance error" refers to the difference between the actual number of heads and the expected number (half the number of tosses).

Understanding Chance Error

  • The equation is: number of heads = half the number of tosses + chance error.
  • The absolute size of the chance error tends to increase as the number of tosses increases.
  • However, relative to the number of tosses, the chance error decreases.
  • For example, with 100 tosses, the chance error is likely to be around 5, but with 10,000 tosses, it's likely to be around 50.
  • Multiplying the number of tosses by 100 multiplies the likely size of the chance error by approximately 10 (the square root of 100).

Key Takeaway

  • As the number of tosses increases, the difference between the number of heads and half the number of tosses (chance error) gets larger.
  • The difference between the percentage of heads and 50% gets smaller.

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