## Announcements

New! Homework 6 solutions posted (under Solutions in the navigation to the left; needs username and password found on the Canvas site for the course).

In office hours today I discovered that I had a misconception about how option `extendInt` of R function `uniroot` works. I went back and looked at all of the examples that used it, and they just happen to be correct, despite my misconception. Careful reading of the help page for this function says option `extendInt = "upX"` means you think the function you are trying to find a zero (root) of is strictly increasing in the neighborhood of the root. And `extendInt = "downX"` for strictly decreasing. But you can always use `extendInt = "yes"` if you are not sure.

Course notes about Data Scraping modified to use R package `rvest` rather than R package `htmltab` (which we found out during the quiz is no longer available. So now we can do problem 1 on quiz 4. The homework now says to do it using the method described in the new notes.

This course has no textbook to buy, but we do consider the free book that comes with every version of R (see under Textbook on the Course Info page) a textbook. Nor do we have any course materials not posted on this web site. Since this web site has not been updated for 2022, the materials may change. But you do not need to purchase any course materials or look elsewhere.

## Announcements for Previous Years

### XKCD Statistics

The xkcd cartoon in the course notes isn't the only one that is about statistics. The web site explain xkcd, exists to explain xkcd cartoons that have too much science or too much pop culture or too much whatever (in some cases too much statistics) for some people to understand or just some esoteric details that people want to know about (and in a few cases, all the contributors to this web site can't quite explain some detail). It indexes xkcd cartoons that deal with statistics.

### Talk to the Bear

I told a student in office hours about talk to the bear. This is just a reminder to tell the story to the whole class.

### About R

A very interesting talk by Martin Mächler (who is on the R core team), which is not required viewing for the class, just interesting. It is titled Seven guidelines for good practices in R programming, and the guidelines are

1. Work with source files!
2. Keep R source well-readable & maintainable
3. Do read the documentation
4. Do learn from the masters
5. Do not Copy & Paste!
6. Strive for clarity and simplicity
7. Test your code
Note that none of these is about any particular feature of R or any particular bit of statistics. They are all about good programming. Rules 1, 3, and 7 are already being emphasized in this course, but the rest are important too. BTW, this talk contains the best explanation of why you should use `<-` rather than `=` for assignment in R.

## Quizzes

Quiz Date
Quiz 1 Friday, Sep 23
Quiz 2 Friday, Oct 7
Quiz 3 Friday, Oct 21
Quiz 4 Friday, Nov 11
Quiz 5 Monday, Nov 28
Quiz 6 Friday, Dec 9

There will be no final exam. All quizzes are in the usual classroom at the usual class time.