60 likes | 212 Views
STA107. Monday April 7 th. 10:00am – 12:00pm. IB 3 45. plant paradise • jenga • therapy dogs • exh -“auction”. free healthy snacks • study space • live music • crafts . tea • appreciation cards • exam prep • sneaker squad . www.fb.com/utmExamJam.
E N D
STA107 Monday April 7th 10:00am – 12:00pm IB 345 plant paradise • jenga • therapy dogs • exh-“auction” free healthy snacks • study space • live music • crafts tea • appreciation cards • exam prep • sneaker squad www.fb.com/utmExamJam www.utm.utoronto.ca/exam-jam
0.1 0.9 0.8 coke pepsi 0.2 Example • Given that a person’s last cola purchase was Coke, there is a 90% chance that his next cola purchase will also be Coke. • If a person’s last cola purchase was Pepsi, there is an 80% chance that his next cola purchase will also be Pepsi. STA107 Lecture 26Markov Chain Probabilities transition matrix:
Given that a person is currently a Pepsi purchaser, what is the probability that he will purchase Coke two purchases from now? Pr[ Pepsi?Coke ] = Pr[ PepsiCokeCoke ] +Pr[ Pepsi Pepsi Coke ] = 0.2 * 0.9 + 0.8 * 0.2 = 0.34 ? Coke Pepsi ?
Given that a person is currently a Coke purchaser, what is the probability that he will purchase Pepsithree purchases from now?
Assume each person makes one cola purchase per week • Suppose 60% of all people now drink Coke, and 40% drink Pepsi • What fraction of people will be drinking Coke three weeks from now?
k Step Transition probabilities p(k)(ij) = P(Xn+k = j|Xn = i) • entry i,j in the matrix Pk gives k-step transition probabilities, p(k)(ij)