RESOURCES
ScheduleEXAMS
Midterm Quiz
MonTues, July 2021
Final Quiz
FriSun, Aug 1416
TEACHING TEAM
cs109sum1920staff @ mailman.stanford.eduInstructor
Oishi BanerjeeInstructor
Cooper RaterinkTA
Tim GianitsosANNOUNCEMENTS
This quarter we are providing you the opportunity to make up your grade on early problem sets. You have the option of completing something we call the Stanford Probability for Computer Scientists Contest. Please see details on this Ed post.
The final problem set is now available. You will implement two machine learning algorithms, Naive Bayes and Logistic Regression. You will then use these algorithms to make predictions on heart tomography, Netflix movies and ancestry data.
The Final Quiz for CS109 is coming up: It is FridaySunday, Aug 1416, 5pm5pm Pacific. We have given you a 48hour timeslot, but the quiz should correspond to about 34 hours of active work time, depending on your preparation and process. While the quiz will focus on material after lecture 11, you could be tested on any CS109 material we have covered by the end of the course.
The best way to study is to work through the practice exams and section handouts. This linked webpage also has quiz administration details and review session materials.
If you have an emergency situation where you are unable to set aside a few hours to complete the exam in this timeslot, please email Oishi and Cooper at any time. We will try our best to accommodate you. If you have OAE accommodations you would like to use for the exam, please email us ahead of time. Information about OAE midterm accommodations will be sent out closer to the quiz date.
The CLT says that if $Y$ is the sum of $n$ iid random variables (which all have expectation $\mu$ and variance $\sigma^2$) then:
The proof is beyond the scope of the class. A friendly CS109 student from a few quarters ago (Sophia Furfine) made a video of the proof in case you are curious!
The penultimate problem set is now available! This problem set has only 8 questions. 

We're interested to know what you think of CS109 so far. We invite you to fill out an anonymous feedback form here: https://forms.gle/1rTgrVAEKJCBSakP6. We'll keep the form open through Wednesday night, July 29.
The Midterm Quiz is released and on the exam page. The takehome, openbook, opennotes exam is to be completed individually, and is due Tuesday, 7/21 5pm Pacific time.
The quiz should correspond to about 23 hours of active work time (plus any typesetting). The Gradescope assignment submission portal will be up through the end of the 24hour window, so please make sure your final submission is uploaded by then. Also please make sure to tag your PDF submission pages to each question answered.
If you have an emergency situation where you are unable to set aside a few hours to complete the exam in this timeslot, please email Oishi and Cooper at any time. We will try our best to accommodate you.
A quick note: If your LaTex template is broken, please redownload and try again. We fixed a small bug a few minutes into the quiz.
Problem Set #4 has been released early to help you prepare for the midterm quiz! It has you predict flu or cold based on binary symptoms and risk factors. There is a line drawn on the pset to indicate which material will be on the midterm.
Problem Set #3 has been released! It uses real probability density functions from the IPCC Climate Change report, and has you analyze a bloom filter (a probabilistic datastructure). The partial answerchecking will be up on Gradescope soon. Pset 3 is due Friday, July 17, 1:00PM Pacific Time.
The Midterm Quiz for CS109 is coming up: It is MondayTuesday, July 2021, 5pm5pm Pacific. It should correspond to about 23 hours of active work time depending on your preparation and process. The quiz will cover material up to and including lecture 11, which includes Problem Sets 1, 2, 3, and part of Problem Set 4. PS4 will be released so that you have extra practice before the midterm.
The best way to study is to work through the practice exams and section handouts. This linked webpage also has quiz administration details and review session materials.
If you have an emergency situation where you are unable to set aside a few hours to complete the exam in this timeslot, please email Oishi and Cooper at any time. We will try our best to accommodate you. If you have OAE accommodations you would like to use for the exam, please email us ahead of time. Information about OAE midterm accommodations will be sent out closer to the quiz date.
Once a week you have the option to meet in a small group section. Our wonderful TA Tim will be hosting the first weekly optional section today at 12:301:20pm PDT. It will be a great time to discuss fun/challenging combinatorics and basic probability problems. Please try to make it if this is something that sounds useful to you. You can find the Zoom link on this page.
Congratulations on finishing PSet #1 (or coming close)! Problem Set #2 has been released! This problem set is just 9 problems to adjust for your workload in this course. Here is a Latex template for pset 2. This pset has a larger coding portion, so we've released a second Python review session you can find on the Python for Probability handout page. We will release a "partial answer checking" resource for the written portion on Gradescope soon.
Problem Set #1 has been released! It is due Wednesday, July 1 at 1:00pm Pacific. Submission will be via Gradescope with entry code MN7X4B. Office hours will start today, and the office hours calendar will have times and Zoom links.
You are encouraged to write up your problem sets using LaTeX. Templates for each Problem Set are located on their respective webpage. See this installation guide and intro to LaTeX. Though you may install LaTeX, it is often much easier to use an online LaTeX editor. A great option is: overleaf.com.
There is a programming problem on this problem set you will complete in Python and submit to an autograder on Gradescope. We've released resources, including a recorded intro tutorial from a previous quarter, on how to use Python for CS109. Please see the Python for Probability handout for these Python resources.
Welcome to CS109! We are looking forward to a fun quarter. Class starts Monday, June 22, at 1:30pm PT Online. Online Zoom lectures will be recorded and posted to Canvas if you cannot attend the live sessions.
Course planning survey: To help us help you in this exciting Summer 2020 onlineonly quarter, please fill out this survey form that asks for your timezone, your technological accessibility situation, and your course expectations. This form is completely optional and is intended to inform how we can better structure CS109 to meet your learning goals and accessibility needs this quarter.
Course schedule: The Course Schedule page shows you the topics that we are going to cover in CS109 and the corresponding readings. We will also post materials from lecture on the schedule page. The schedule will be accurate as of the current day. In other words, things later on the schedule may change slightly.
We put together some handouts to help you understand where we are going to go in CS109 and how we plan to get there.
The Administrivia handout has details on course logistics. Read this to get a sense for what CS109 is going to entail. Please see the FAQ for any questions that may come up. If you have more questions, feel free to ask them on Ed or during our first synchronous class session.
The Staff / Office Hours page has contact information for TAs (TBD) and the office hour calendar. Office hours will start Tuesday, June 23.
Once the quarter starts, we will release information about weekly sections. These will be towards the later end of the week, and completely optional. We hope attending these sections will deepen your understanding of CS109 material and encourage you to engage in problemsolving conversations and discussions with your classmates.
Week  Monday  Wednesday  Friday 

1

Jun 22 1: CountingRead: Ch 1.11.2 
Jun 24 2: Permutations and Combinations
Watch: 1_all, 2_all
Out: PSet #1 
Jun 26 3: Axioms of Probability
Watch: 3_all

2

June 29 4: Conditional Probability and Bayes
Watch: 4_all

Jul 1 5: Independence
Watch: 5_all
Out: PSet #2

Jul 3 Independence Day (Observed)No Class 
3

Jul 6 6: Random Variables I
Watch: 6_all

Jul 8 7: Random Variables II
Watch: 7_all
Out: PSet #3 
Jul 10 8: Continuous Random Variables
Watch: 8_all
Due: PSet #2 
4

Jul 13 9: The Normal Distribution
Watch: 9_all

Jul 15 10: Joint Distributions
Watch: 10_all
Out: PSet #4 
Jul 17 11: Independent Random Variables
Watch: 11_all
Due: PSet #3 
5

Jul 20 12: Joint RV Statistics
Watch: 12_all
Midterm 
Jul 22 13: Conditional RVs
Watch: 13_all

Jul 24 14: Continuous Joint Distributions
Watch: 14_all
Out: Pset #5 
6

Jul 27 15: More Cont. Joint and CLT
Watch: 15_all
Due: Pset #4 
Jul 29 16: Sampling/Bootstrapping
Watch: 16_all

Jul 31 17: Parameters and MLE
Watch: 17_all
Out: Pset #6 
7

Aug 3 18: Beta
Watch: 18_all
Due: Pset #5 
Aug 5 19: Maximum a Posteriori
Watch: 19_all

Aug 7 20: Naive Bayes
Watch: 20_all

8

Aug 10 21: Gradient Ascent and Linear Regression
Watch: 21_all

Aug 12 22: Logistic Regression
Watch: 22_all
Due Thursday 1PM: Pset #6 
Aug 14 23: (no class)Final Quiz 