Joint random variables

• Admistrivia:
  • Extra problems to do for "fun"
  • Any questions from the homework?
  • Read the first few paragraphs from each section 5.1, through 5.5
  • You should have read 4.1 - 4.7 already

• Independent random variables
  • Two die rolls (start with the marginals, compute the joint)
  • Testing for independence (years experience (1,2,3) vs scored didn't score)

    	1	2	3
    0	.2	.1	.1	.4
    1	.3	.1	.2	.6
    	.5	.2	.3	1.0

• Conditional probability: What is conditional probably of scoring for a person with 3 years of experience?
• Example:

  Suppose X = daily temp. in degrees F

  Let Y = (X - 32)*5/9 = daily temp in degrees C

  Suppose E(X) = 72, SD(X) = 18

  • What is E(Y) and SD(Y)?
  • What is correlation between X and Y?

• Work with cards
• permutations = order matters
• combinations = order doesn't matter

Last modified: Wed Oct 27 10:16:55 EDT 1999