Difference between revisions of "161-A1.1"

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|<math>\frac{1}{2}</math>
 
|<math>\frac{1}{2}</math>
 
|<math>\log_2\left(2\right)=1\,\mathrm{bit}</math>
 
|<math>\log_2\left(2\right)=1\,\mathrm{bit}</math>
 +
|-
 +
| You rolled a seven on rolling a pair of dice.
 +
|<math>\frac{6}{36}</math>
 +
|<math>\log_2\left(6\right)=2.58\,\mathrm{bits}</math>
 +
|-
 +
| Winning the Ultra Lotto 6/58 jackpot.
 +
|<math>\frac{1}{40400000}</math>
 +
|<math>\log_2\left(40400000\right)=25.27\,\mathrm{bits}</math>
 
|-
 
|-
 
|}
 
|}

Revision as of 00:14, 14 September 2020

Let's look at a few applications of the concept of information and entropy.

Surprise! The Unexpected Observation

Information can be thought of as the amount of surprise at seeing an event. Note that a highly probable outcome is not surprising. Consider the following events:

Event Probability Information (Surprise)
Someone tells you .
You got the wrong answer on a 4-choice multiple choice question.
You guessed correctly on a 4-choice multiple choice question.
You got the correct answer in a True or False question.
You rolled a seven on rolling a pair of dice.
Winning the Ultra Lotto 6/58 jackpot.

Student Grading

How much information can we get from a single grade? Note that the maximum entropy occurs when all the grades have equal probability.

  • For Pass/Fail grades, the possible outcomes are: with probabilities . Thus,

 

 

 

 

(1)

  • For grades = with probabilities , we get:

 

 

 

 

(2)

  • For grades = with probabilities , we have:

 

 

 

 

(3)

  • If we have all the possible grades with probabilities , we have:

 

 

 

 

(4)