Announcements

August 1, 2002 (1:16 AM)
I added an outline of what the course covered. I could add more to this website (in particular, updating the reading guide), but it seems rather silly to do so at this point, and besides I need to focus my attention on some work I should do for the statistical consulting center, and on the upcoming fall semester (for which I'll have to craft a new version of the nonparametrics course, since I'm having to change books (and I haven't taught the course in 3 years)).
July 26, 2002 (9:41 PM)
Some students requested that I post answers to the last few homework problems, and I have now done so on the homework solutions web page.
July 25, 2002 (11:20 PM)
Well, for some of you, it's Christmas in July --- I decided to boost the bottom five finishers one letter grade increment (say, B to B+) from what I had planned to do yesterday. I'm not happy with the poor performance on the exam, nor the homework scores, for the bottom bunch of the class, but I decided to adjust for the fact that the workload and level of difficulty were greater than I had originally planned.
July 24, 2002 (11:40 PM)
I finished grading last night, and nearly have the final letter grades determined, but I think I'll give the matter a bit more consideration, and then submit grades sometime Thursday afternoon. (Since we now submit grades electronically, I think you can get into the system and check your grades very soon after I submit them.) The median on the final exam is 59.4%, which a bit bit lower than my Tuesday afternoon guess of 65%. Six students did really excellent, ranging from 86.4% to 96.8%, but five scored less than 50%, which is disappointing. For overall course grades, there will be 7 grades of A, and 1 A-; but except for those 8 grades, I will wait until tomorrow before making decisions about the letter grades. Unfortunately, some of the students who didn't do well on the exam, also didn't do as well on the homework problems as I would have liked to be the case (largely because not enough problems were submitted after the July 4th break), and so the distribution of overall course averages has a strong bimodal appearance, making it hard to justify too many grades of A- and B+. Still, given that graduate courses that meet twice a week in the summer are very tough for many students to manage, anytime that the "class GPA" is at least 3.5 (which will be the case), I feel that as a group, the class learned a lot. I plan to add some more material to the course web site later, but I'll wrap up the loose ends from this course by Monday morning so that I can focus on other matters (like the upcoming fall semester, and some work I need to do for the university statistical consulting center).
July 23, 2002 (3:31 AM)
I added to the homework solutions web page, and posted answers for Quiz #8, and answers for Quiz #9. Note that even though the course officially ends with the conclusion of the final exam, I'll continue to add to this web site for a while, providing information about grades for the class, and perhaps posting more homework solutions.
July 22, 2002 (12:54 AM)
I edited the information about the final exam web page. I don't plan to add any more hints about what to study.
July 21, 2002 (2:48 AM)
I edited the information about the final exam web page. You can note that 14 of the 20 small problems/questions deal with just 3 relatively small portions of the course material.
July 19, 2002 (9:54 AM)
I added to the information about the final exam web page. (Note: Later today, people from the university computing support staff are planning to switch my e-mail system. Based on what I've heard from others who have already been switched over, I anticipate some problems, and it may be the case that I won't be able to use e-mail over the weekend. But I do plan to be over in the Central Module for my extra office hours on Sunday and Monday.)
July 18, 2002 (12:49 AM)
I added a few more corrections to the class notes, and I added a bit more information about the final exam. (I still intend to add a lot more information about the final.)
July 17, 2002 (6:23 PM)
I've posted answers for Quiz #13, and also information about your final quiz averages. In addition, at the very bottom the the home page for this course website, I've added links to information about R and S-PLUS, both of which students can get for free.
July 16, 2002 (1:38 AM)
I created a web page pertaining to the final exam. I'll add to it over the next 6 days. Please note that it states that I'll have extra office hours on Sunday and Monday, but I won't have any this Thursday.
July 15, 2002 (6:23 PM)
I posted some hints and comments for Problem 16, because I'm a bit worried that some of you may mess it up otherwise. Also, I finally posted the answers to Problem 14 on the homework solutions web page. If you desire more details about Problem 14, then maybe it'll be best to just track me down. While I do hope to provide you with more details concerning solutions to the homework problems eventually, tonight I'm going to turn my attention to making up the final exam, and making a web page to provide you with some guidelines for studying for it.
July 14, 2002 (4:35 PM)
I edited my hints and comments for Problem 21 (with the new comment, a "be careful" warning of sorts, in color). I'm in the process of writing about 8 pages of notes on cross-validation and other methods of model selection and assessment to close the lecture presentations with. Try to read over the material I gave you on robust regression and my study comparing regression methods, since I might try to present that stuff in about 60 minutes or so, in order to save some time to present the new material I'm preparing. Since I may have to present those 8(ish) pages of notes rather quickly, you might find it easier to follow the discussion if you read over the section on cross-validation in the article by Efron and Gong.
July 12, 2002 (4:01 AM)
I forgot to give you the solution to Problem 18. Since only 7 students got it right, you may want to check out the answer I posted on the homework solutions web page before doing Problem 19 (since one needs to use the exponential reference rule to do part of Problem 19). (I have a hard copy version of the solution that I can distribute on Tuesday.) I posted the solution for Problem 15 as well. Also, I posted an explanation of the answers to Thurday night's quiz, and I put one more correction to Section I of the class notes on the corrections web page.
July 11, 2002 (4:27 AM)
I edited an explanation of the answers to Quiz #11 to state that I'm not going to count off for the poorly worded question if you didn't supply the answer I was looking for. Also, I put one correction to Section I of the class notes on the corrections web page, and I added a suggestion for Problem 19 to the homework web page. Finally, I added some comments about what I'll cover in lecture today to the bottom of the reading guide web page.
July 10, 2002 (4:55 AM)
I posted an explanation of the answers to Quiz #11, and an explanation of the answers to Quiz #14. Overall, the scores weren't real good, but that's pretty much been the case all along. I suspect that people do spend a decent amount of time preparing for the quizzes, and so it must be that they are a bit trickier than I want them to be. In the end, except for one guy who may have a perfect quiz average once I drop 4 low scores, most of you will have similar scores, and so really the quizzes won't separate you in the determination of the final course grades. I'm still planning on giving more grades of A and A- than I usually do, since I think your effort has been good and I consider you to be an above average group of students. Plus, I want my grading to be fair for students who came into the course with only minimal preparation (while satisfying the prerequisite), and that being the case, it's not surprising that some of you with a lot of courses under your belts will do well gradewise. One reason for the flood of HW problems distributed near the end of the course is to give some students a chance to work hard and earn a good grade despite having made several silly mistakes previously on the homework. Of course, I hope that some of you who have done very well on the homework so far will also try the remaining HW problems, but I won't hold it against you if you choose to coast a bit over the next week or two. As long as you get close to 160 points on the HW problems that count towards your grade (after I drop the low scores like I have indicated), that'll be fine. (Since the HW scores have generally been good (median score on the problem you turned in Tuesday night is 14.9 out of 15), unlike the quizzes, I don't think the homework has been too hard or too tricky, and so I do think it's reasonable to expect you to be close to 160 points after I drop a lot of low scores.) It's turned out that the homework problems have been longer and more numerous than I guessed would be the case six weeks ago, but by having you work hard on the homework, I can overlook less than stellar performance on the quizzes and the exam and still give a lot of good grades --- plus, if you do the minimum number of problems well, I do think the amount of homework is less than usual for one of my graduate classes.
July 9, 2002 (3:29 AM)
I updated information about quiz component of course grade and information about homework component of course grade, now that I have all of the remaining quizzes ready to go, and I have the last of the HW problems to distribute in class today. You can find the remining HW problem due dates and new links to hints and comments about several problems on the homework web page. I have also added some more solutions to the homework solutions web page. Finally, let me ask that you help me remember to do a few things in the days ahead: on the days that you turn in Problems 18 and 20, I want to give you solutions at the end of class (so that they can possibly be of help to you as you do other HW problems that are related); and help me remember to do the course evaluation either this Thursday or next Tuesday (since in the summer the end of the semester seems to swoop in quickly, and I'm worried that with so many different things in my bags, the evaluation form packet will get pushed aside as I race to work in all of the quizzes and the overhead presentations).
July 8, 2002 (12:14 AM)
I've added some more comments about Problem 14. (The new stuff is at the bottom of that web page, in a different color from the original comments I posted on June 29.) (Note: I plan to be at GMU another 24 hours straight, so I may indeed make more adjustments to the web site later today.)
July 5, 2002
I added information about Quiz #14, which I may give as a 2nd quiz on Tuesday, July 9, if there is time, to the quiz web page. (I also added a link to an explanation of a previous quiz to the quiz web page.)
July 4, 2002
I posted HW Problem 18, which is a simple one that is due on Thursday, July 11. (I will give you the solution to this problem at the end of class on July 11 if you ask me for it. You may want to check your answer against the solution before doing part of Problem 19.) I also posted some information about Quiz #11, which will be given at the start of class (so don't be late) on Tuesday, July 9. I made a slight change to some information about Quiz #13, since it is doing Problem 16, instead of Problem 14, that will help you prepare for the quiz. (For Problem 14, I've worked out the Satterthwaite approximation in the class notes, but for Problem 16 you'll need to work it out for yourself, and by doing so, use some knowledge that is relevant to one of the problems on Quiz #13.) Finally, I updated the corrections web page.
July 3, 2002
I posted explanations for the correct answers to last night's quiz.
July 1, 2002
I created a web page pertaining to the quizzes. Of particular interest to you may be the links to studying suggestions for the 10th, 12th, and 13th quizzes. (I have yet to decide what Quiz #11 will cover.)
June 29, 2002
I've made some hints and/or comments about Problem 14.
June 27, 2002
A short while ago a student in the class brought my attention to a mistake I had in one of my macros --- when I converted my macro that did the Welch F test for the I = 3 case to handle the I = 6 case, I forgot to change the 1st df from 2 to 5, and thus my p-value for that test on p. E12f of the class notes is incorrect. The correct value should be 0.0567388. (One of the reasons I didn't give you a bunch of macros like I do in STAT 554 is that I wanted to have you help me confirm that I got my marcos prepared without bugs. Of course, I also think it is good practice for you to write some macros for the various test procedures --- you should learn a lot more by writing your own macros than by just using ones that you're given.) I'll note this correction on my corrections web page, but since I'm giving you the correction above, there is really no point in going there now (since I didn't make any other changes today).
June 26, 2002
I've made some hints and/or comments about Problem 11 and some hints and/or comments about Problem 12. I'll add similar web pages for some of the other HW problems later.
June 25, 2002
I've updated the HW web page to show due dates for several problems that I'll be distributing in class tonight. Please read the comments I've inserted at the bottom of the HW web page. I'll organize the comments better, and add some hints, a bit later, but if you read them over in their present form they might prevent some of you from making some mistakes.
June 24, 2002
I've came up with a plan for this week's quizzes.
June 23, 2002
I gave some indication of what I'll cover Tuesday (after I finish through p. E29 of the notes I distributed) in the reading guide (go to the bottom to see the plan for Tuesday). Also, I noted some small mistake in Miller's book on pages 108 and 109. So if you're keeping track of the mistakes I have found in that book, go to my web page with comments about Miller's book to see the mistakes I recently found on pp. 108-109.
June 22, 2002
I corrected the macro that I used to produce p. E29 of the class notes, incorporating a continuity correction for the J-T test. The new p-value is about 7.2 * 10-5, instead of 6.3 * 10-5. I'll give you a new (corrected) p. E29 next class.
June 21, 2002
I updated the corrections to the class notes web page, posted a solution for Problem 8 on the HW solutions web page, posted the due date for Problem 13 on the HW web page, and created a web page which explains the answers to the questions on Quiz #7.
June 20, 2002
I'll remind you that a high school graduation is scheduled to start at the Patriot Center at 7:30 PM, and so you might run into heavier than usual traffic coming onto campus. Also, in case I forget to tell you in class, I'm not absolutely certain that I don't have any mistakes in my Minitab output in the class notes (although I do check things rather carefully, so I'll guess there aren't many mistakes). I'm having to work long hours while I'm tired just to get the materials ready for class each time, so it could be that a mistake is occassionally made. (For example, I forgot to add the continuity correction when I got the p-value on p. E29 for the JT test.) So if you check your work carefully, and you can't match my results, let me know as soon as possible. Also, check the web site from time to time to see if I announce any more mistakes.
June 19, 2002
12 of 14 students got HW Problem 7 correct. One of the wrong answers is close, so I suspect it's off due to sloppiness, but one student's answer is way off. I've posted the answer, and show how one can easily get the jackknife estimate of standard error using Minitab, on the HW solutions web page. (Once the data is in a column, one can actually compute the standard error estimate using a single let command.) My Minitab scheme can be easily altered to work for the situation of HW Problem 8, so you can use it to check your work if you wish to do it some other way. I'm only going to allow about 5 minutes for the quiz on Thursday, so I encourage you to review these simple guidelines for choosing between jackknifing and bootstrapping. The estimation settings dealt with on Thursday's quiz may be a bit more complex than those covered on last Thursday's quiz, but if you understand the guidelines, it should be no problem to correctly deal with the slightly more complicated settings. (9 of 14 got Tuesday's quiz 100% correct, and 4 of the other 5 only missed the one question that I commented on. I'll explain the correct answers in class on Thursday if you remind me to do so.) I posted some more corrections to the class notes and also pointed out on this web page an error in the Efron and Gong article that an observant student found (and I also corrected a very small (almost of the typo sort) error I had on tht web page). If you handed in HW Problem 8 ahead of time, I will give them back to you ungraded along with Problem 7 that I've graded, so please be sure to resubmit it.
June 18, 2002
I posted due dates for the 3 problems I'll distribute in class tonight on the homework web page.
June 17, 2002
I created a web page with some comments about the Efron and Gong article that Tuesday's quiz will be based on, and a web page which explains the answers to the questions on Quiz #5 (which you took last Thursday, and is similar to the quiz I'll give this coming Thursday). To prepare for Tuesday's quiz, read the first 3 sections of the Efron and Gong article. Don't worry so much about the mathematics or the parts of those sections that pertain to material that I didn't mention in class. Also, although you should study Tables 1 and 2 so you can compare the performances of the bootstrap, jackknife, and parametric estimators, for the quiz I won't focus on anything specific from the tables. (But for the final exam, I may have a problem or two which deals with the tables, so it may pay off later if you spend time now trying to fully understand the tables and the Monte Carlo studies done by the authors.) By looking at my web page with some comments about the Efron and Gong article, you might be able to come up with a good guess about the focus of Tuesday's quiz (which will have 4 or 5 True/False questions that should be easy, and so I plan to only allow about 5 minutes for the quiz (so there won't be a lot of time to read the article during the quiz). For Thursday's quiz, study this web page and see the appropriate parts of the class notes for additional details. Below are some more announcements.
June 15, 2002
I updated the reading guide to indicate what I'll cover this coming week (go to the bottom of the web page to see where I indicated that I'll cover certain parts of Ch. 3 of Miller's book) and also include some more references on bootstrapping, and I updated the web page listing corrections to the class notes (with all of the new corrections being at the bottom of the web page). (Please let me know if you spot any other errors in the notes, or other materials that I give you.) I also fixed a couple of typos (nothing of importance) on web pages linked from the syllabus, as well as corrected the time period for the final exam on a web page linked from the syllabus (since the exam period goes until 10:15 PM). I advise that you review the material from Sec. C of the class notes about choosing between the jackknife and bootstrap estimates of bias and variance (and standard error). (Go here to see a short summary.) No one got all 5 parts of Thursday's quiz correct. As I said in class, next Thursday (after you've gotten back the quiz you took) I'll give a similar quiz about choosing between the jackknife and the bootstrap. Please remind me on Tuesday to explain the reasons for the quiz answers after I give back your papers to you.
June 11, 2002
I updated the homework web page and the reading guide, and added a web page listing corrections to the class notes and a homework solutions web page.
June 10, 2002
I only plan to add one more page to my notes on bootstrapping, and one more page to my notes on jackknifing, and so we should finish up those topics (for now --- they will be revisited later) in about an hour during Tuesday's class. The next topic will be dealing with dependent observations, the subject matter of Sec. 1.3 of Miller's book. In the process of discussing dependence due to blocking, I'll get into subsection 3.5.4, which makes use of material on pp. 95-96. When you have time, you might want to look over any pertinent comments I have about Chapters 1 and 3 in my notes about the Miller book. (Just tonight I have pointed out a mistake on p. 104 that I hadn't noticed before.) Although my lecture material on dependence gets a bit messy in places, I'm not going to have you do any HW problems based directly on the messy part. What I hope is that the main message comes through: if the data comes from depenent random variables, and appropriate adjustments are not done, then tests and confidence intervals can be rather misleading.
June 7, 2002
I edited the homework web page to include for due dates for the problems I've distributed. Also note, in case there is any confusion about what I announced in class, although I plan to give quizzes next week like those described on the sheet containing HW problems 5, 6, 7, and 8, I will reverse the order, so that the quiz I have described for Tuesday will be given Thursday, and the one described for Thursday (based on the first 2 pages of the Science article), will be given on Tuesday.
June 1, 2002
The scores on the first quiz weren't so good. The next quiz will be 10 True/False questions based on these two topics: (1) the improved estimate of bias; (2) bootstrap confidence intervals based on approximate normality and using the bootstrap estimate of standard error. Since people did miss more than I had expected them to on the first quiz, I'll go over the quiz at the beginning of class, and give a 5 minute review of the basic bootstrap estimate of bias --- maybe one more time through the explanation will work wonders for some people's understanding. Of course, you'll get more out of the review if you spend some time thinking about the estimate of bias on your own. Go here to see a short explanation that may be helpful. Also, note that I updated the homework page to show the due dates for the problems due on Thursday. (Two problems are due Tuesday, and two are due Thursday.)
May 29, 2002
I edited the syllabus and the linked info about the quizzes to reflect the fact that part of the 1st quiz will be closed books and notes. (The rest of the quizzes will be open books and notes.)
May 28, 2002
I edited the syllabus, adding three links that give more information about the grading. Also, I put the due date of the first HW problems on the homework web page.
May 24, 2002
I edited the reading guide to give you a better indication of what you can read to help prepare for the first lecture now that I've changed my mind about the order in which I will cover topics during the first 2 or 3 weeks. Really, it's not that important that you read anything prior to the first lecture, but if you have time, check out the article that I list which is available in e-journal format.
May 11, 2002
I edited the reading guide to give some indication of what you can read to help prepare for the first lecture.
April 26, 2002
If you want to take the course this summer, be sure to register for it by May 13 --- if too few students have registered, it may be cancelled.