TC3 → Stan Brown → Statistics → Spr12 ME50 → Broadcast Emails
revised 22 May 2012

# Emails to the Class

Summary: Broadcast mails are sent to your TC3 address. They’re also archived here for those who may be having mail problems.

Please check your mail frequently. (If you’ve set up forwarding to another address, you still have to log in to your TC3 email at least once a semester or the account will go inactive.)

## 22 May: Course debriefing

Greetings, statistics wizards! Thanks for all your hard work through the semester — I know it was a rough ride for some of us.

Thanks also for filling out your Course Debriefings. Probably the strongest message is that I need to find a way to have more in-class activities and less lecture. I’ll work on that, but if any of you have any specific suggestions I’ll welcome them.

Student Responses to Course Debriefing.

And whatever else you do, have a great summer!

## 17 May: Grades have been posted

Greetings, statistics wizards! Grades have been posted and you may access them through myTC3/myInfo.

If you would like the details of how your grade was computed, you can request and receive that information by replying to this email in your TC3 account.

## 29 April: Steps 5 and 6 of hypothesis test

Greetings, statistics buffs!

Sorry for multiple emails today. But I noticed some of you had problems with steps 5 and 6 of hypothesis tests on the quiz and the ESP Lab. This is a heads-up so you can correct any misunderstandings before the Chapter 11 quiz on Tuesday and of course before doing your Field Project.

Please see Proper Conclusions to Your Hypothesis Tests, which is on the Web page and was also part of the printed handout for Chapter 10. I recommend you put the correct step 5 on your cheat sheet.

Regarding step 6, there are two possibilities: either you state your H1 as proved (“My partner and I have ESP”) or you cannot reach a conclusion (“It’s impossible to say whether my partner and I have ESP or not”). You never accept H0. If your p-value was greater than α you always write your non-conclusion in neutral language, mentioning both possibilities equally.

You might also find it helpful to review the Top 10 Mistakes of Hypothesis Tests on the Web page, particularly number 5 and number 3.

## 29 April: Review for the exam

Greetings, statistics buffs! I’m sending this information by email so that we won’t have to take class time to go over it. As always, feel free to ask any questions in email.

This coming Tuesday, 1 May, we’ll have a regular class with the Chapter 11 quiz and then Cases 6 and 7 from Chapter 12. I’ll also be distributing your detailed grade computation so far.

The following Tuesday, 8 May, we’ll have a Chapter 12 quiz, or not; see my email of 25 April. We’ll have project presentations, and then our review session. I’ll also ask you to fill out a Course Debriefing.

The review session will be entirely driven by your questions. You can ask about concepts or particular problems; it’s up to you. I know the timing is not ideal, but it’s the only time we have together before the exam on 15 May.

I have a review guide and a lot of review problems for you on the Web, under Handouts » Review for the exam. They are jumbled up, not in order of the course material, just as the exam will be. You’ll also want to look back at your past quizzes and homework as a guide to what you didn’t master the first time.

The exam itself will be 6:30–9:20 on Tuesday, 15 May, in our regular room. There will be about 20 to 30 questions, and most students finish their exams around 8:30 to 9:00. I’ll post grades within 48 hours, and send out an email to let everyone know. At that point (not sooner, please), you can email me a request for a detailed grade computation.

Remember, the exam is your second chance to show that you’ve mastered the material. If you do substantially better on the exam than you did on the quizzes, I’ll give the exam more weight in your grade and the quizzes less weight.

## 28 April: Two-population confidence intervals

Greetings, statistics buffs!

You may have trouble writing good interpretations of confidence intervals in Cases 3, 4, and 5. They can be extra tough when you have one minus sign and one plus sign in the bounds of the interval. Always remember that in addition to the level of confidence you need both size and direction of the effect. And of course you have to show that the requirements are met, unless you already did that for a hypothesis test with the same data.

The examples we did in class are all on the Web page in PDF format, and there are also five extra examples in Confidence Intervals for Two Populations.

## 27 April: Nag, nag, nag

Greetings, statistics buffs!

Time is growing short for your Field Project Plan. Every semester, there is a mad rush on Tuesday, when there is not time for every student’s plan to be discussed, revised, and approved. Don’t let that happen to you — get your plan to me today or tomorrow, so that you can get the revisions done and get your approval Sunday or Monday.

If you want the chance to earn 15 points of extra credit, you need to have your approval by the end of the break on Tuesday. (The time after class is reserved for questions about the class material and is not available for project plans.)

Again: if you wait till Monday or Tuesday to start the process, there’s a strong risk that you won’t get your plan finished and approved in time. So please get started now.

## 25 April: Will there be a quiz on Chapter 12?

Greetings, statistics buffs!

Next week, expect a quiz or homework inspection on Chapter 11. But what about the following week and a quiz on Chapter 12? That’s actually up to you. I’ll take a vote next week so that you know what to expect.

In favor of a quiz: If you know there isn’t one, you might not study the chapter and then you might miss the Chapter 12 question(s) on the exam. In the past, that has been the pattern for many students. Also in favor of a quiz for some of you: if you’re doing better in inferential statistics than you did in descriptive, it can raise your average.

Against a quiz: it takes some class time, you won’t actually get your grade till the following week (exam week), and — it’s a quiz.

You can probably think of other arguments. From my perspective, a quiz is more work but I think it probably promotes your learning of Chapter 12. The choice will be yours.

If you do vote for a quiz, it will be a standard quiz, with the possibility of homework inspection instead. If it happens to be one of your lowest two, it will be dropped. It will count just like any other (except your bottom two) for determining whether you can skip the final exam.

## 21 April: This coming Tuesday’s quiz

Greetings, statistics buffs!

Just a reminder: the quiz will cover the entire handout, not just pages 14–16.

As always, please feel free to ask me any questions in email.

## 21 April: Field Project

Greetings, statistics buffs!

Here’s a reminder of last Tuesday’s announcements about the Field Project.

The project itself is due at the last class before the final, 8 May. Please use the grading protocol on the Web page to make sure that you do everything that’s required.

That evening, you have the option of presenting your project to the class for up to 15 points of extra credit. (See the Field Project document for what to present.) However, you can do this only if your project follows an approved Field Project Plan.

The deadline for getting your Field Project Plan approved is the close of the break period on 1 May. Caution: Your first plan may not be approved; most students find that it takes one or more revisions before the plan is correct. So you need to submit your Field Project Plan earlier, either in person on 24 April or in email during the week 25–30 April. If you wait till 1 May to give me your first plan, there may not be time to make needed revisions and get it approved.

The Field Project Plan is not graded, but it’s important because it’s your security. Working from an approved plan, you will know that your project is on the right track. If you don’t have an approved Field Project Plan, you won’t be able to present your project to the class for extra credit, but you can still get help from me on request. The risk there is that you might choose a project that doesn’t actually meet the assignment, which would be devastating to your grade.

Before you even write up a Field Project Plan, I recommend that you bounce your idea off me, in the form of the claim that you will test. Example: “I want to test whether the actual distribution of colors in Plain M&Ms matches what the company says.” There’s no formal deadline for this, but I suggest you should do it by 24 April or as soon as possible after that, to give yourself time to write your Field Project Plan and get it approved.

## 21 April: Tips for the ESP Lab

Greetings, statistics buffs!

1. The key to the analysis is the data type: binomial or numeric. To determine this, think about your sample, not overall but each data point in the sample. Is each data point a number or a yes/no?

2. To identify the population, reflect that the sample is always drawn from the population. Your sample is 100 instances of something; what? Those 100 instances must be drawn from a larger population of the same sort of thing. How can you describe that population, and how large is it?

3. Use the grading protocol in the lab as a checklist, so that you do everything that is required for the assignment.

4. English counts on the ESP Lab and the Field Project. If your skills in written English are shaky, consider working with a writing tutor in the Baker Center.

## 8 April: Chapter 8 quiz results

Greetings, statistics buffs!

I’m glad to say that five students earned A’s on the quiz, and two of those earned better than 100%. But overall the results bother me a lot: N = 20, median = 4.4, mean = 6.4, s.d. = 5.1; number of papers without a name: 1.

On the Chapter 7 quiz two weeks ago, I used a homework problem but changed the description. On the Chapter 8 quiz last Tuesday, I used a homework problem (page 402 number 8) and even kept the same description, yet the majority of the class got it completely wrong. It’s hard for me to see how that can happen if you’re doing the homework and checking your answers.

I want to see everyone in this class succeed, and I’ll help you every way I know how. But ultimately it comes down to your commitment — you need to put in the work. I don’t know another way to say it: if you want a prayer of passing this or any math course, the homework is crucial. It’s how you know whether you’ve understood the material, so you don’t just “do the homework” and close your book with a sigh of relief. You check your answers and resolve any misunderstandings.

For your checklist for success, please look again at Your To-Do List (red sheet from the first night, or on the Web).

As always, I’ll be happy to answer any questions that I can in email, until Tuesday lunchtime.

## 4 April: Borrowing calculators

Greetings, statistics buffs!

The word from the head of tutoring is “The calculators are loaned from the first floor service desk in the Commons and also from technology support upstairs in the Commons.”

If you do need to borrow a calculator for the evening, allow yourself enough time to get it from one of those desks and also be in our classroom early enough that I can inoculate it with the programs. Caution: If possible, get a TI-84 (any model) or a TI-83 Plus. In the past I have had some difficulties with older TI-83s not being able to accept the programs, and the odds are better with a later model. I can’t be responsible if you have a loaner calculator that can’t accept the programs.

## 29 Feb: Quiz results

Greetings, statistics buffs!

Results of the Chapter 4 quiz: N = 20, Med= 11.1, μ = 9.9, σ = 4.3. If you would like to know your quiz grade before Tuesday, drop me an email.

Thought for the day:
Schoolwork is like exercise: the more days a week you do it, the more benefit you get.

## 26 Feb: Quiz results and late papers

Greetings, statistics buffs!

Reminder: pencil and eraser are suggested for quizzes.

Reminder: when there’s any significant computation, you must show your work for full credit on a correct answer, or for possible partial credit on an incorrect answer.

For the Chapter 3 quiz, N = 20, Med = 7.0, μ = 7.4, σ = 4.4. Obviously this is less than terrific. I’ve added some more common mistakes to the solutions page.

Problem 6 (parameters of birth weights) was the downfall for many of you. I’m disappointed, because two homework problems (page 174 #6, page 176 #6) were similar, and the practice quiz also had a similar problem. I really expected almost everyone to get this one.

If you didn’t, ask yourself: am I doing all the homework and checking my answers? If you’re not checking your answers, you’re depriving yourself of feedback when you do the homework.

Remember, you should make up your cheat sheet before starting the homework. That’s how you find out if your cheat sheet is missing something.

If you did the homework and got it right, you may need more practice. Make it part of your plan to work the practice quiz each week, observing the time limits, and check your answers.

For the labs, I have decided to grant an automatic 10-minute grace period. If you turn them in by 6:40 they will count as on time. The purpose of the penalty for lateness is to discourage letting a lab make you late to class. But since anyone who’s late will miss some quiz time as well as professional-conduct points, I don’t think you need to lose further points on the lab if you’re a minute or two late.

This will apply to last week’s Sleep Lab as well as to future labs when there is a quiz at the start of class. It won’t apply to the Field Project unless we have a Chapter 12 quiz the night the project is due. (The class will decide whether to have a Chapter 12 quiz.)

As always, if unforeseen circumstances beyond your control make you late, please discuss the situation with me privately.

## 20 Feb: Quiz results

Greetings, statistics buffs!

I’m happy to report that the Chapter 2 quiz results look much better than Chapter 1’s: N = 22, Med = 14, μ = 12.6, σ = 3.0. There were 13 A’s.

The biggest trouble spot for most of you was the bar graph. Please review the requirements for bar graphs and histograms, so that you don’t make the same mistakes on the Sleep Lab.

I’ve added common mistakes to almost all the questions on the solutions page.

Reminder: We’re in room 224 starting tomorrow. Please sit where you will want to sit for the next few weeks, as I will make up a seating chart tomorrow from where you are actually sitting.

As always, please feel free to ask any questions in email, or during the 5:30 to 6:30 hour in the classroom.

## 16 Feb: This ’n’ That

Greetings, statistics buffs! Herewith a few small housekeeping details. Some were mentioned in class; some were not.

• Make sure you have the Spring 2012 version of the Sleep Lab. In the past some students somehow found an old version, and the assignment does change slightly from semester to semester.
• If you want a review of the calculator procedures we did on Tuesday, please see the links under Handouts — Chapter 3.
• Please consider working through the calculator procedure in the handout I gave you Tuesday. Then you’ll know where all the buttons are and you won’t get lost in class.
• Starting next week we will be in room 224.

See you Tuesday! As always, feel free to email me questions. Remember also that the 5:30–6:30 time is office hours.

## 14 Feb: Corrections to Sleep Lab assignment

Greetings, statistics buffs!

If you have already printed off your Sleep Lab, please make the following corrections to the Data Collection paragraph:

• Before “Record the answers”, insert the sentence ”Add yourself as the 25th data point.”

I made these correction to the Web page about noon on Tuesday, 14 February, so if you print the page any time after that you should have the corrected version.

## 11 Feb: Calculator practice

Greetings, statistics buffs!

If you’re feeling intimidated by the calculator, I recommend that you work through Sample Statistics on TI-83/84 in the Web handouts under Chapter 3.

Yes, we’ll be doing it together Tuesday night, but you’ll have a much easier time on Tuesday if you’ve already been through the procedure on your own when you can find all the keys at your own pace. Then on Tuesday you can concentrate more on what it all means.

## 9 Feb: Bar graph and histogram

Greetings, statistics buffs!

The chart from the side board is now on the Web under Handouts for Chapter 2. Here’s a direct link: Histogram and Bar Graph Compared.

## 5 Feb: Reminders

Greetings, statistics buffs!

We glossed pretty quickly over sampling and nonsampling errors last Tuesday. Don’t let that make you think they’re not important. They’re extremely important; we just didn’t need to spend much class time on them because your book does a good job of explaining them.

The class voted to have the quiz right at 6:30, so it’s extra important to be on time. Please make use of the 5:30 to 6:30 time to get your final questions answered. But again, if you have a lot of questions or “big picture” questions, you’ll want to take care of them beforehand, in email or in the Baker Center. If you try to do too much in the hour before class, you’ll probably have a hard time retaining any of it.

See you Tuesday! As always, please feel free to ask me any questions in email — the sooner the better.

## 21 Jan: Welcome to MATH200!

Greetings, statistics buffs!

You may want to get a jump on the textbook and calculator that you’ll need for the course. Please look here for the requirement:
www.tc3.edu/instruct/sbrown/stat12a/letters.htm#L1217

Also please note that we’ve had a room change: the class will meet in room 212.

As always, feel free to email me with any questions about anything.

## 17 Dec: Calculator and textbook requirement

Greetings, statistics buffs! I’m looking forward to meeting you this spring.

For those who like to plan ahead, I want to let you know what you’ll need for the class.

Our textbook is Sullivan, Michael, Fundamentals of Statistics 3/e (Pearson Prentice Hall, 2011), ISBN 0-321-64187-6 or 978-0-321-64187-8, or the “second custom edition” in the TC3 bookstore, ISBN 0-558-91325-3 or 978-0-558-91325-0. Yes, you really do need to read the textbook in addition to attending class. Either buy the printed textbook, or if you’re really comfortable reading a whole textbook online you can buy just the Student Access Kit and access course number brown64282 at coursecompass.com. You need one or the other, not both.

Past experience shows that the TC3 bookstore tends to sell out of textbooks, so don’t wait till the last minute to get yours. Of course, if you can get your book from another source you may save some money. There are also numerous textbook rental sites on the Web. You can also rent an electronic edition (images of all pages of the textbook) at CourseSmart.com, but be careful not to rent so early that the book expires before the end of the course.

The required calculator is any model TI-83 or TI-84. Buy on price; the few additional statistics features in the TI-84 Plus Silver Edition are not significant for our class. (The TI-82, 85, 86 can’t do what you need. A TI-Nspire will work if you run TI-84 emulation, but you’ll be spending more than you need to. If you have a TI-89, TI-92, or Voyage 200, please see the Web page Can I Use a TI-89 for Statistics Class?)

Most of the “big box” retailers carry TI-83s or TI-84s, and if you have the option of shopping there you can usually find a bargain. Or you may be able to rent one at rentcalculators.org or similar sites.