#--------------------------------------------------------- # File: MIT18_05S22_in-class24-script.txt # Author: Jeremy Orloff # # MIT OpenCourseWare: https://ocw.mit.edu # 18.05 Introduction to Probability and Statistics # Spring 2022 # For information about citing these materials or our Terms of Use, visit: # https://ocw.mit.edu/terms. # #--------------------------------------------------------- Class 24 Bootstrap Jerry Slide 1: Intro Slide 2: Announcements/Agenda (3 minutes) Exam comments: Class ave 90, std dev 9. Will publish results on gradescope soon. Announcements/Agenda 3 minutes Slide 3: Empirical distribution (2 minutes) Example 2: the histogram is made with n = 100 samples Slide 4: Review of resampling (3 minutes) Slide 5: Bootstrap principle for the mean (3 minutes) Don't dwell: tell them they will get board practice for this Slide 6: Empirical percentile bootstrap CI (4 minutes) Don't dwell: tell them they will get board practice for this Slide 7: Empirical basic bootstrap CI (1 minute) This is in notes, we won't do this in class. Just say words 'algebraic pivot' Will discuss that with parametric bootstrap Empirical Percentile CI is more important for us Slide 8: Which empirical is is best? (2 minutes) We'll emphasize the percentile bootstrap Slide 9: CONCEPT QUESTION (5 minutes) Emphasize can be used for any statistic Jen Slide 10: BOARD QUESTION (Work: 10 minutes, discuss 6 minutes Median: Interpolation: How quantile() works: There are 8 values, the first is at quantile 0, the second is at quantile 1/7 etc. So the .1 quantile is .1/(1/7) of the way from the first element to the second. That is xbar^*_{0.1} = 2.83 + (.1/(1/7))*(4.00-2.83) = 2.83 + .7*(1.17) = 3.65 Median is similar Slide 11: Percentile bootstrapping in R (4 minutes) Point out it's essentially 5 lines of working code Slide 12: Parametric bootstrap ( 4 minutes) Similar: generate the samples from parametrized distribution estimate variation -delta_start pivot to get confidence interval --like algebraic pivot for z CI etc Slide 13: R code (4 minutes) **Quickly Same code except data generation line and use of delta_star Note theta_hat requires division by n since mean of binomial is n*theta Note pivot in last line Slide 14: BOARD QUESTION (Work: 10 minutes, Discussion 5 minutes) Discussion: (If time) show code from previous slide