a quick intro to bayesian thinking 104 frequentist approach 10/14 probability of 1 head next: =...

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Page 1: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51
Page 2: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51
Page 3: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51

A quick intro to Bayesian thinking

Page 4: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51

10 4

Page 5: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51

Frequentist Approach

10/14

Probability of 1 head next: = 0.714

0.714 0.714X

Probability of 2 heads next: = 0.51

Page 6: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51

Bayesian Approach

Rev. T. Bayes ( 1707 - 1761 )

Page 7: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51

Posterior

LikelihoodPrior

Normalising Constant

Page 8: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51

Frequentist:

Bayesian:

Likelihood(p) -> parameter p is a fixed constant.

Posterior ∝ Likelihood(p) x Prior(p)

Page 9: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51

Beta Prior for p

Page 10: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51

Beta ∝ Binomial x Beta

How would you bet ?

Results : p = 48.5%

Page 11: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51
Page 12: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51
Page 13: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51
Page 14: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51

Example US election

Page 15: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51

Actual Results

Page 16: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51
Page 17: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51
Page 18: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51
Page 19: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51

Bayesian● Prior knowledge

● Updatable with new information

● Data are fixed● Parameters are described

probabilistically

● Complex to compute

Frequentist● No prior information to

model● Data is a repeatable

random sample● Parameters are fixed

● Easy to compute

Page 20: A quick intro to Bayesian thinking 104 Frequentist Approach 10/14 Probability of 1 head next: = 0.714 0.714 X Probability of 2 heads next: = 0.51

Questions?

“Applying Bayesian functions ….” TNG - S4 Ep10