Access Millions of academic & study documents

Random variables

Content type
User Generated
Showing Page:
1/22

Sign up to view the full document!

lock_open Sign Up
Showing Page:
2/22

Sign up to view the full document!

lock_open Sign Up
Showing Page:
3/22

Sign up to view the full document!

lock_open Sign Up
End of Preview - Want to read all 22 pages?
Access Now
Unformatted Attachment Preview
STAT 22000 Lecture Slides Random Variables Yibi Huang Department of Statistics University of Chicago Outline Coverage: Section 2.4 in the text. • Random Variables • Expected Value • Standard Deviation • Linear combinations of random variables 1 Random variables Random Variables A random variable is a numeric quantity whose value depends on the outcome of a random event • We use a capital letter, like X , to denote a random variable • The values of a random variable are denoted with a lowercase letter, in this case x, e.g., P (X = x ) Example 1. Let X be the number of heads in 2 tosses of a coin. The possible outcomes are {HH , HT , TH , TT } and X (HH ) = 2, X (HT ) = 1, X (TH ) = 1, X (TT ) = 0 Example 2. Let Y be the number of tosses required to get a head. The possible outcomes are S = {H , TH , TTH , TTTH , TTTTH , . . .} Y (H ) = 1, Y (TH ) = 2, Y (TTH ) = 3, Y (TTTH ) = 4, . . . 2 Discrete and Continuous Random Variable There are two types of random variables: • Discrete random variables often take only integer values • Example: Number of credit hours, Difference in number of credit hours this term vs last • Continuous random variables take real (decimal) values • Example: Cost of books this term, lifetime of a battery 3 Probability Distribution A probability distribution of a discrete random variable is a list of its possible values and the probabilities that it takes on those values. Value of X x1 x2 x3 Probability p1 p2 p3 ...
Purchase document to see full attachment
User generated content is uploaded by users for the purposes of learning and should be used following Studypool's honor code & terms of service.
Studypool
4.7
Indeed
4.5
Sitejabber
4.4