CSC107 - Lab 1
Wisdom of Crowds

Assigned Jan 15th
Due Jan 22nd Beginning of Class

Show your work on all questions for full credit.

Numerical Wisdom

Question 1

Five people guess the number of bones in the human body. Four of their answers are 160, 190, 210 and 250, and their average is 208. What is the missing guess?

Question 2

Seven people playing Wits and Wagers are asked the following question: How many times do the Beatles sing the word "Yeah" in the song She Loves You?

The players answers are 18, 23, 27, 31, 36, 44, and 53. The correct answer is 29.

  1. What is the average guess?
  2. What is the collective error?
  3. What is the average individual error?
  4. What is the prediction diversity?

Question 3

Why will the collective error never be greater than the average individual error?

Majority Wisdom

Question 4

Three people answer the question "Which is taller on average, an ostrich or an emu?" If each person is 70% correct when they answer questions like this, what is the probability that the majority answer is correct?

Question 5

How many ways are there to choose 4 people from a class of 7?

Question 6

What is the probability that with 7 people voting, 5 are exactly right, given that each person is 70% correct?

Question 7

Nine people answer the question "Which has a higher average weight, an African or Asian elephant?" If each person is 51% correct when the answer questions like this, what is the probability that the majority answer is correct?
© Mark Goadrich 2009, Centenary College of Louisiana