The formula for the CV(k) error incorrectly showed a 1/n in the front of the sum, where it should have been a 1/k, as in the lesson.

This has been changed on the D.4 summary sheet, and on the flashcard for this formula. The flashcard will automatically update in the flashcard app, and the printed flashcards have been updated, although you may just want to write in this change rather than to try to reprint a single card.

Additionally, more problems have been added this week to lesson D.5.1, D.6.1 and D.6.2.

Recent Additions:

D.4.5: 3 more new problems

D.5.2: 6 new problems

D.5.3: 8 new problems

D.5.4: 5 new problems

Next up: D.5.1, D.4.4, D.6.1, D.6.2

Recent corrections:

D.4.3 #9, numbers and answer choices adjusted.

E.2.6 #6, solution typo corrected, negative in the first equation should have been positive.

C.2.7 #10 from the pdf was a duplicate and was removed, this was already reflected in the problem system.   This adjusts the problem numbers in the C.2.7 pdfs and in the video solutions tab.

C.3.2 #9 was removed as a duplicate. This adjusts the problem numbers in the C.3.2 pdfs and in the video solutions tab.

E.3.1 #4, typo corrected, solution is 0.122, not 0.112.

C.2.6 Answer sheet changed to reflect correct answer choice for #5

D.3.7 #3, typo corrected in solution, the final F-stat has 26 denominator degrees of freedom.

D.5.4 #6, solution typo corrected, 0.74 should have been 0.75.

D.5.3 #5 Solution typo corrected, 7.2 should have been 7-2.

Thanks to the person that let me know that C.1.7 #3 was a near duplicate of another problem in that set.   Interestingly, both of these were old exam problems, again emphasizing the value of spending time working old exam problems.

I’ve removed #3, and everything else will renumber automatically in the problem system, so if you are using the problem system, you shouldn’t notice this change.  However, if you are using the pdfs, you will want to grab a copy of the new C.1.7 handouts so that your problem numbers on the pdfs will match the numbering in the solutions tab for this lesson.

In terms of updates, I’ve added 7 problems to D.1.1, and 1 to each of D.4.5, and D.6.3, as well as 3 more to E.2.2.   More to come!

I’ve finished adding some new problems for the lessons in E.3.  The topics here were a later addition to the Exam S syllabus that are persisting over to the MAS-I syllabus too.   Even though they have been on the syllabus for S (and now MAS-I) for more than a year, only one question has ever been asked from this material.

So far, we can’t tell if that means that this material won’t be tested often, or if the exam writers just haven’t gotten around to it.   My guess is that we will soon start to see one question from E.3 appearing on most exams.

Next up, I’m going to dive into making new problems for the unit D lessons that are new to MAS-I and don’t have very many problems yet.

Please don’t use the number of problems that appear in the lessons on the material that is new to MAS-I (So, mostly D.4-D.6) as a way to decide which of those lessons are more important.   The main thing that the number of problems indicates is how long the topic has been on the syllabus and how many older exam questions have been asked about it.   For the new topics, we won’t really know how the exam writers are focusing their attention for quite some time.

By the way, I’m currently answering forum questions nearly every morning first thing, and also at other times during the day.  As a result, most questions are being answered in less than 24 hours, and some even within one or two hours.  Please stop in and ask me your questions – especially as you make that leap from the Unit B and C material to the more advanced material in Unit D.   There is some heavier stuff in those Unit D lessons, so don’t hesitate to come and get help!

I corrected a formula on slide 2 of lesson C.2.4 today, as well as the C.2 summary sheet for the same formula.  Fortunately, this is a formula that has never been used in any problem, so it is unlikely to cause problems even if you happen to have already memorized the incorrect version.

The error was that the paired variance in the case where the variances of the underlying samples are known did not account for the covariance between the samples due to the pairing.   The correction is to include the covariance term.

As I said, this is not likely to cause a problem, since it has never come up, but the corrected handouts, lessons, and summary sheet are now uploaded to the course.

The rest of the recent updates are newly added problems to the lessons in section B.5, lessons C.1.8-C.1.10, and lesson C.2.9.

I’ll be continuing to add problems to the lessons that are new to MAS-I over the course of the month.  At the moment I will be prioritizing new problem writing, so if you see a problem that you would like to have a video solution for, please let me know.