Math 160

Introduction to Applied Statistics

Fall 2007

  • Homework assignments
  • Daily notes
  • Useful class links
  • Fun stuff
  • Course project
  • Check your scores (data last updated December 20, 2007)
  • Homework assignments

    For each homework assignment, a target date is given. This is the date of the class in which I will ask for questions on this section.
    Section Problems to do Target date Quiz Comments
    1.1 #1.3, 1.13, 1.17, 1.18, 1.37, 1.38, 1.39 Friday, September 7 1 See daily note for information on data for last three problems.
    1.2 #1.41, 1.43, 1.45, 1.47, 1.49, 1.58, 1.59, 1.71, 1.77 Monday, September 10 1 For 1.59, compute at least one mean and standard deviation "by hand". You can use a calculator to do the arithemtic.
    1.3 #1.78, 1.80, 1.81, 1.82, 1.83 Tuesday, September 11 1 For 1.83, you'll need to read and understand the material on pages 68-69 of the text.
    1.3 #1.87, 1.96, 1.97 Thursday, September 13 2
    1.3 #1.93, 1.99, 1.102 or 1.103, 1.104 or 1.105, 1.115 Friday, September 14 2 Where you have a choice, choose the problem that concerns the test you took (ACT or SAT).
    1.3 #1.119, 1.120, 1.121, 1.124 Monday, September 17 2
    2.1 #2.1, 2.3, 2.9, 2.10, 2.13 Tuesday, September 18 2 For 2.13, see note below on Minitab.
    2.2 #2.23, 2.31, 2.38, 2.39 Thursday, September 20 -
    2.3 #2.43, 2.45, 2.53, 2.58 Friday, September 21 -
    2.4 #2.63, 2.69, 2.71, 2.81, 2.82 Monday, September 24 -
    2.5 #2.85, 2.88, 2.93 Tuesday, September 25 -
    3.1 #3.3, 3.5, 3.6, 3.7 Monday, October 1 3
    3.2 #3.12, 3.13, 3.19 Monday, October 1 3 You can use Minitab to generate a list of random numbers. See note below.
    3.3 #3.37, 3.41, 3.47, 3.48, 3.53, 3.55, 3.56, 3.57 Tuesday, October 2 3
    3.4 #3.66, 3.67, 3.69, 3.75 Thursday, October 4 4 For 3.75, you will do by hand what we saw going on in the applet during class. It's a bit tedious to do this by hand, but essential in order for you to understand what's going on.
    4.1 #4.1, 4.3, 4.7 Monday, October 8 4 For 4.3, you can use the data we collected in class a few weeks ago. The data we collected is available in a Minitab file called M&MCounts.mtw in \\Alexandria\stats\Jackson\Data. For 4.7, you can use real dice if you have them around.
    4.2 #4.11, 4.13, 4.15, 4.21, 4.25 Monday, October 8 4
    4.2 #4.14, 4.27, 4.30, 4.31 Tuesday, October 9 4
    4.3 #4.43, 4.45, 4.48 Tuesday, October 9 4 We did parts (a), (b), and (c) of Problem 4.48 in class last week as an example.
    4.3 #4.53, 4.55, 4.56, 4.57 Friday, October 12 -
    4.4 #4.59, 4.61, 4.63, 4.65 Monday, October 15 -
    4.4 #4.67, 4.69, 4.70, 4.71, 4.73, 4.75, 4.79, 4.81 Tuesday, October 16 -
    5.1 #5.1, 5.3, 5.5, 5.13 Thursday, October 25 5
    5.1 #5.17, 5.19 Friday, October 26 5 See note below.
    5.1 #5.20, 5.23 Monday, October 29 5
    5.2 #5.33, 5.37, 5.39, 5.41, 5.43 Thursday, November 1 -
    6.1 #6.1, 6.5, 6.7, 6.9, 6.13, 6.16, 6.25 Friday, November 2 - Regarding Problem 6.13: 80 minutes per week? How about 80 minutes per day!
    6.2 #6.35, 6.39, 6.41, 6.43, 6.49, 6.51, 6.54, 6.55, 6.57 Monday, November 5 -
    6.3 #6.73, 6.74, 6.77, 6.82, 6.83, 6.84 Tuesday, November 6 -
    7.1 #7.1, 7.10, 7.11, 7.13, 7.21, 7.25 Monday, November 12 6 For Problem 7.25, you do not need to do the optional part (d).
    7.1 #7.29, 7.31, 7.37 Tuesday, November 13 6 For Problem 7.31, use the matched pairs idea described beginning on page 459 in the text.
    7.2 #7.53, 7.73, 7.77, 7.81, 7.83 Monday, November 19 7
    8.1 #8.3, 8.5, 8.7, 8.11, 8.13 Tuesday, November 20 7
    8.1 #8.9, 8.29, 8.30 Monday, November 26 7
    8.2 #8.31, 8.33, 8.37, 8.43, 8.47 Thursday, November 29 -
    8.2 #8.44, 8.48, 8.51, 8.52, 8.53 Friday, November 30 -
    9 #9.1, 9.9, 9.19, 9.27, 9.33, 9.38, 9.39 Monday, December 10 8 For Problem 9.1, you'll need to read about the language of joint and marginal distributions in Section 9.1.

    Daily notes

    Monday, December 10

    Topics: return Exam #4; questions on Chapter 9 problems
    Text: Sections 9.1, 9.2
    Tomorrow: Quiz #8

    If you use the Minitab data files that are supplied with the text for the Chapter 9 problems, you'll want to use Stat: Tables: Cross-Tabulation and Chi-Square.... In the dialog box that opens, you'll need to identify the appropriate worksheet columns for

    As an example, here's what the set-up should look like for Problem 9.38:

    ChiSquareDialog.gif

    You'll also want to select a few options available using the Chi-Square... button. Here's a picture of the options you'll probably want:

    ChiSquareOptions.gif

    We will begin class tomorrow with Quiz #8.

    Friday, December 7

    Topics: χ2 statistics
    Text: Section 9.2
    Tomorrow: Chapter 9 problems

    I've assigned problems from Chapter 9. You'll probably want to use Minitab (or something equivalent) for some of these problems. You can use Stat: Tables: Chi-Square Test (Table in Worksheet)...

    If you've finished collecting data for your course project, you should begin analyzing it and thinking about your report. Sometime over the weekend, I'll post a handout with some guidelines for your report.

    Thursday, December 6

    Topics: associations among categorical variables; two-way tables
    Text: Section 9.1
    Tomorrow: χ2 statistics

    Chapter 9 does not have problems sets for each section. All of the problems are at the end of the chapter. I'll assign some of these after tomorrow's class

    The next step in the course project is to submit a copy of your data by tomorrow. You can submit a photocopy of handwritten data or a digital copy of a Minitab (or Excel or similar) file as an e-mail attachment. If you have not finished collecting data, submit a brief report on your plans.

    Tuesday, December 4

    Topics: Exam #4
    Text: Chapters 7 and 8
    Tomorrow: associations among categorical variables

    Monday, December 3

    Topics: review for Exam #4
    Text: Chapters 7 and 8
    Tomorrow: Exam #4

    Exam #4 will be tomorrow (Tuesday, December 4) from 8:00 am to 9:20 am. The exam will test your understanding of material from Chapters 7 and 8. It will not cover material from any of the optional subsections, the "Beyond the Basics" sections, and Section 7.3. For the exam, you can bring

    In preparing for the exam, you should

    For more practice, you could look at exercises at the end of each chapter. Here's some that I think might be useful based on a quick read of the odd-numbered problems:

    Friday, November 30

    Topics: questions on 8.2 problems; a way to organize thinking about the material in Chapters 7 and 8
    Text: Section 8.2
    Tomorrow: review

    Exam #4 (the last one!) will be on Tuesday, December 4 from 8:00 am to 9:20 am. The exam will test your understanding of material from Chapters 7 and 8. It will not cover material from any of the optional subsections, the "Beyond the Basics" sections, and Section 7.3. For the exam, you can bring

    In preparing for the exam, you should

    For more practice, you could look at exercises at the end of each chapter. Here's some that I think might be useful based on a quick read of the odd-numbered problems:

    Thursday, November 29

    Topics: Quiz #7; the pooled estimate for comparing proportions
    Text: Section 8.2
    Tomorrow: ??

    In class today, we looked at the pooled estimate that can be used when doing a significance test for the null hypothesis that two population proportions are equal. Yesterday, we did an example of a significance test using separate (i.e., "unpooled") estimates. The text uses the pooled estimate for all of its examples and problems. You should use the pooled estimate if you want to compare your results with answers given in the back of the text.

    In Minitab, you can do two-proportion inference using Stat: Basic Statistics: 2 Proportions.... The default setting uses the separate estimates. To use the pooled estimate for a significance test, go to Options... and check the box "Use pooled estimate of p for test" Note that this option will not change the confidence interval calculation since confidence intervals must be calculated using the unpooled estimate.

    I've assigned additional problems from Section 8.2.

    Tuesday, November 27

    Topics: inference for comparing proportions
    Text: Section 8.2
    Tomorrow: Quiz #7; more on inference for comparing proportions

    Yesterday, we talked through questions on a handout to review the "big picture". Here's my version of brief responses to each question.

    In class today, we looked at a method for producing confidence intervals with large samples. For smaller samples, there is a plus-four method. This is similar to the plus-four method for a single proportion from Section 8.1. I'm leaving it up to you to read about the version in Section 8.2

    We'll start class on Thursday with Quiz #7.

    Monday, November 26

    Topics: review of the "big picture"; questions on Section 7.2, 8.1 homework
    Text: Section 8.1
    Tomorrow: inference for comparing proportions

    We did not discuss new ideas today so I have not assigned additional homework.

    Tuesday, November 20

    Topics: questions on Section 8.1 homework; the "plus four" statistic for a proportion; sample size for a desired margin of error
    Text: Section 8.1
    Tomorrow: inference for comparing proportions

    As we discovered in class, the answer in the back of the text for Problem 8.7 (a) is incorrect. The value given there is the standard error, not the margin of error. To get the margin of error, you must multiply by the appropriate critical z value.

    I've assigned a few more problems from Section 8.1

    In class, we looked at three options for getting a proportion confidence interval for a proportion:

    I believe the 1-PropZInt function on a TI-83/84 computes a confidence interval based on a normal approximation for the sample proportion.

    Part (b) of Problem 8.7 asks you to think about the issue of non-response in a survey. A large non-response can bias the results if the group that does respond does not represent the full group in ways that are relevant to what's being studied in the survey. If you do a survey and have a high non-response rate, you should do some analysis to understand potential bias. Some details on this kind of analysis are at the section Nonresponse Bias Analysis of the Statistical Standards for the National Center for Education Statistics.

    Monday, November 19

    Topics: return Quiz #6; questions on Section 7.2 homework; inference for a proportion
    Text: Section 8.1
    Tomorrow: more on inference for a proportion

    In class, we looked at two examples using what our text calls the large sample confidence interval method. Tomorrow, we'll look at the plus four method. I've assigned a few problems from Section 8.1. For these, you can use the large sample method. I'll assign additional problems from Section 8.1 after class tomorrow.

    Friday, November 16

    Topics: more on inference for difference of two means
    Text: Section 7.2
    Tomorrow: more on inference for difference of two means

    Thursday, November 15

    Topics: Quiz #6; inference for difference of two means
    Text: Section 7.2
    Tomorrow: more on inference for difference of two means

    I did not assign additional problems today. I will assign problems from Section 7.2 tomorrow after we have talked more about inference for the difference of two means.

    Tuesday, November 13

    Topics: questions on Section 7.1 problems; robustness of t-procedures
    Text: Section 7.1
    Tomorrow: Quiz #6; inference for difference of two means

    I have not assigned additional problems today. Between now and class on Thursday, you should make sure you do and understand the assigned problems from Section 7.1. Part of this is being able to state conclusions in real-world terms. If you work on a problem and aren't sure if what you write is reasonable, you can send me an e-mail with your wording and I'll give you some feedback. For guidance, you can look at the wording of examples in the text. In particular, look at the wording in Examples 6.7, 6.8, 6.11, and 6.12 for how you might phrase conclusions of significance tests.

    The next step in the project will be to do a pilot study. This will involve collecting a small amount of data in order to assess how well your data collection process works and to estimate how long it will take you to collect a full set of data. Based on this, you will write a brief progress report desribing how you pilot study went and any changes you think will be needed for the full study. This will be due next Tuesday. More details are on this handout.

    Monday, November 12

    Topics: return Exam #3; questions on Section 7.1 problems
    Text: Section 7.1
    Tomorrow: more on using the t-statistic

    I've assigned a few more problems from Section 7.1.

    Course Project Warm-up #3 is due tomorrow. E-mail if you have questions or run into difficulties.

    Friday, November 9

    Topics: t-statistic, t-distributions, t-confidence intervals, t-tests
    Text: Section 7.1
    Tomorrow: more on using the t-statistic

    I've assigned some problems from Section 7.1.

    If you have a TI-83/84 calculator, you can get cumulative probabilities for t-distributions. Go to the DISTR menu and select tcdf(. The required arguments for tcdf are a lower bound, an upper bound, and the degrees of freedom. For the example we did in class, we needed the cumulative probabilty between t=-1.4 and t=1.4 for df=4. The input tcdf(-1.4,1.4,4) returns a value of 0.766. The P-value for our example is thus 1-0.766=0.234.

    You can also use Minitab to compute confidence intervals or P-values. You can do this for either the Z-statistic from Chapter 6 or the T-statistic we are now studying. I'll demonstrate this in class tomorrow. If you want to explore this on your own, go to Stat: Basic Statistics: 1-Sample Z... or Stat: Basic Statistics: 1-Sample t.... For each, you have a choice between Samples in columns or Summarized data. Use Samples in columns if you have data in a worksheet. Use Summarized data if you already know the sample mean and sample deviation. If you leave Test mean empty, Minitab will return a confidence interval but not a P-value. You can go to Options... to select the confidence level or select the type of alternative hypothesis.

    Here's the handout with details on Course Project Warm-up #3.

    Thursday, November 8

    Topics: Exam #3
    Text: Chapters 5,6
    Tomorrow: t-distributions

    Tuesday, November 6

    Topics: questions on Section 6.2, 6.3 homework; review
    Text: Sections 6.2, 6.3
    Tomorrow: Exam #3

    Exam #3 will be on Thursday from 8:00-9:20. The exam will test your understanding of material from Chapters 5 and 6. It will not cover material from any of the optional subsections, the "Beyond the Basics" sections, and Section 6.4. This handout has a list of objectives for the exam. For the exam, you can bring

    In preparing for the exam, you should

    For more practice, you could look at exercises at the end of each chapter. Here's some that I think might be useful based on a quick read of the odd-numbered problems:

    I will be available on Tuesday from 1:30 until about 5 pm with the exception of a few advising appointments. On Wednesday, I will be available most of the day except noon to 2 pm and a scattering of advising appointments. Call or email if you want to set up a specific time to meet.

    Monday, November 5

    Topics: questions on Section 6.2 homework
    Text: Sections 6.2, 6.3
    Tomorrow: questions on homework; review

    Note that I added Problem 6.57 to the problems assigned for Section 6.2

    Section 6.3 is descriptive. You are responsible for reading and understanding this material. I've assigned problems from Section 6.3.

    Exam 3 will be on Thursday, November 8 from 8:00-9:20 am. It will cover material in Chapters 5 and 6, omitting Section 6.4.

    In class, someone asked if the idea in Problem 5.54 of using statistical analysis to determine authorship is a joke. It's no joke. There's a field of study called stylometry devoted to use quantitative techniques for determing authorship. This article at Science News has some details and examples.

    Friday, November 2

    Topics: questions on Section 6.1 homework; significance tests
    Text: Section 6.2
    Tomorrow: more on significance tests

    Note that I added Problem 6.25 to the problems assigned for Section 6.1. I have also assigned some problems for Section 6.2.

    The focus of Chapter 6 is the ideas of statistical inference. The two types of statistical inference we will work with involve confidence intervals and significance tests. For now, we are constructing confidence intervals and doing significance tests using some unrealistic assumptions. The point of this is to simplify the computational details so we can focus on the meaning of our results. You should be able to

    and

    Exam #3 will be Thursday, November 8 from 8:00 am to 9:20 am. It will cover material from Chapters 5 and 6.

    Thursday, November 1

    Topics: Quiz #5; questions on Section 5.2 homework; confidence intervals
    Text: Section 6.1
    Tomorrow: significance tests

    In thinking about confidence intervals, you might find it useful to distinguish between

    So far, we have talked about one specific method of constructing confidence intervals. The method we have applies to constructing a confidence interval for a population mean when we know the population standard deviation. The method is based on sample data from a simple random sample. The method gives a correct confidence interval if the population distribution is normal. If the population distribution is not normal but the sample size is large, the method gives an approximately correct confidence interval.

    Tuesday, October 30

    Topics: questions on Section 5.1 homework; more on sampling distribution of sample mean; overview of statistical inference
    Text: Sections 5.2, 6.1
    Tomorrow: confidence intervals

    Quiz #5 is on Thursday. It will include problems from assignments as indicated above. You can bring your notes and a calculator to use. I'll supply values for binomial distributions if needed.

    Your preliminary project proposal is due on Friday. Here's some sources of ideas for project topics:

    Exam #3 will be on Thursday, November 8 from 8:00-9:20 am.

    Monday, October 29

    Topics: questions on Section 5.1 homework; sampling distribution of sample mean
    Text: Section 5.2
    Tomorrow: more on sampling distribution of sample mean; overview of statistical inference

    I'll assign problems from Section 5.2 after tomorrow's class.

    Friday, October 26

    Topics: questions of Section 5.1 homework; approximating a binomial distribution with a normal distribution
    Text: Section 5.1
    Tomorrow: sampling distribution of sample mean

    In class, I mentioned that you can get values for various probability distributions on a TI-83/84 calculator. Details are in the guidebook that comes with the calculator. If you don't have a guidebook, you can download one at the TI calculator site.

    Thursday, October 25

    Topics: binomial model for counts and proportions in a SRS
    Text: Section 5.1
    Tomorrow: approximating a binomial distribution with a normal distribution

    To get probabilities for a binomial distribution in Minitab, go to Calc: Probability Distributions: Binomial... At the top of the dialog box, select Probability. Then, enter a value for Number of trials (this is what we usually label n) and a value for Probability of success (this is what we usually lablel p). At the bottom of the dialog box, choose Input constant and then enter a value (this is what we usually label k). After you hit OK, Minitab will return information the Session window. To get probabilities for more than one value, set up a column of values in a Worksheet window. Then, go to Calc: Probability Distributions: Binomial... Do as above except choose Input column at the bottom and then specify the column you set up.

    The answer for Problem 5.17(b) that is given in the Answer section of the text is based on using the normal approximation for a binomial distribution. We'll talk about this approximation in class tomorrow. For now, you should use an exact binomial distribution so your answer will differ from what's given in text.. You will probably find it convenient to use the Cumulative probability choice in Minitab's dialog box for Calc: Probability Distributions: Binomial...

    Friday, October 19

    Topics: binomial distributions
    Text: Section 5.1
    Tomorrow: binomial model for counts and proportions in a SRS

    We have Fall Break next week so we won't meet again until Thursday, October 25. We will not have a quiz next week. Our next quiz will be Thursday, November 1.

    I've assigned a few problems from Section 5.1. We'll pick up with more of the ideas from Section 5.1 after break.

    Enjoy your break!

    Thursday, October 18

    Topics: Exam #2
    Text: Chapters 3 and 4
    Tomorrow: binomial distribution

    Tuesday, October 16

    Topics: questions on Section 4.4 homework; review for Exam #2
    Text: Chapters 3 and 4
    Tomorrow: Exam #2

    Exam #2 will be on Thursday from 8:00-9:20. The exam will test your understanding of material from Chapters 3 and 4. It will not cover material from any of the "Beyond the Basics" and Section 4.5. This handout has a list of objectives for the exam. For the exam, you can bring

    In preparing for the exam, you should

    I will be available on Tuesday from 1:30 until about 5 pm. On Wednesday, I will be available most of the day except noon to 2 pm and 4 to 5 pm.

    Monday, October 15

    Topics: questions on Section 4.4 homework; means and variances of combinations of random variables
    Text: Section 4.4
    Tomorrow: review

    Exam #2 is on Thursday, October 18 from 8:00-9:20 am. The exam will cover material from Chapters 3 and 4. It will not cover material from any of the "Beyond the Basics" and Section 4.5.

    Friday, October 12

    Topics: the mean and variance of a random variable
    Text: Section 4.4
    Tomorrow: more on means and variances of random variables

    Thursday, October 11

    Topics: Quiz #4, continuous random variables
    Text: Sections 4.2, 4.3
    Tomorrow: the mean and variance of a random variable

    I've assigned a few more problems from Section 4.3. The new problems deal with continuous random variables.

    In the example we started at the end of class, I was trying to show a connection between something familiar (computing the mean of a distribution for a variable) and something new (computing the mean of a random variable). To compute the mean of a distribution of values for a variable, we add up all of the values in the distribution and then divide by the number of values. We can rearrange the arithmetic in this calculation so that we calculate the same number in a new way. The new way is to multiply each possible outcome by the proportion of values with that outcome and then add those results. This is a weighted sum of the outcomes. I'll try to clarify all of this tomorrow.

    Tuesday, October 9

    Topics: questions on Section 4.2, 4.3 homework; a few more probability examples
    Text: Sections 4.2, 4.3
    Tomorrow: Quiz #4; continuous random variables

    We will have Quiz #4 at the beginning of class on Thursday. It will consist of problems taken from homework assignments as indicated in the list above. You can use any notes you bring. You might also want a calculator.

    I have not assigned any new problems today.

    Monday, October 8

    Topics: return Quiz #3; questions on Section 4.1, 4.2 homework; probability examples and rules
    Text: Sections 4.2, 4.3
    Tomorrow: random variables

    I've assigned more problems from Section 4.2 and a few problems from Section 4.3. There will be more from Section 4.3 after tomorrow's class.

    Friday, October 5

    Topics: random phenonena and probability
    Text: Sections 4.1, 4.2
    Tomorrow: probability models

    We started our look at random phenomena and probability. I've assigned problems from Sections 4.1 and 4.2. I'll assign a few more problems from Section 4.2 after Monday's class.

    Thursday, October 4

    Topics: Quiz #3; return Exam #1; questions on 3.4 homework; connecting population parameter and sample statistic
    Text: Section 4.1
    Tomorrow: starting in on probability

    I'll wait until tomorrow to assign new problems so you can focus on finishing Course Project Warm-up #1. In the meantime, you should read Section 4.1

    Here's the Oxford English Dictionary on die as a noun:

    1. With plural dice. (The form dice (used as pl. and sing.) is of much more frequent occurrence in gaming and related senses than the singular die.)
      1. a. A small cube of ivory, bone, or other material, having its faces marked with spots numbering from one to six, used in games of chance by being thrown from a box or the hand, the chance being decided by the number on the face of the die that turns uppermost. Also, a cube bearing other devices on its faces, or a solid with more or less than six faces (see quots.).
        b. pl. The game played with these; esp. in phr. at (the) dice.
    So, die is the singular. Dice is used as both plural and singular.

    Tuesday, October 2

    Topics: questions on 3.1, 3.2, 3.3 homework; getting information on a population from a sample; parameter vs. statistic; sampling distribution
    Text: Section 3.4
    Tomorrow: starting in on probability

    For the Course Project Warm-up, you will need to compute BMI from height an weight data. If you use the Caclculator feature in Minitab, you will need to understand the syntax for multiplication and powers. For multiplication, use *. For example, if you want to multiply 5 times a variable called MyVariable, use 5*MyVariable. For powers, use **. For example, to square MyVariable, use MyVariable**2.

    Monday, October 1

    Topics: questions on 3.1, 3.2 homework; analyzing a news report on an observational study; a bit about sample surveys
    Text: Sections 3.2, 3.3
    Tomorrow: first ideas on how we learn from samples

    Friday, September 28

    Topics: gathering and producing data
    Text: Sections 3.1, 3.2
    Tomorrow: more on producing data

    To generate a list of random integers in Minitab, use Calc: Random Data: Integer.... This will bring up a dialog box in which you can enter the number of rows of data, a storage column, a minimum value, and a maximum value.

    Here is the assignment handout for Course Project Warm-up #1. Come talk with me or send e-mail if you have questions or difficulties on the assignment.

    Thursday, September 27

    Topics: Exam #1
    Text: Chapters 1 and 2
    Tomorrow: producing data

    Much of the material in Chapter 3 on Producing Data is descriptive. We'll outline main ideas in class and then you will have responsibility for reading details in the text. We'll clarify the details as we discuss questions from reading and assigned homework.

    Tuesday, September 25

    Topics: questions on Section 2.5 homework; review
    Text: Chapters 1 and 2
    Tomorrow: Exam #1

    Exam #1 will be on Thursday from 8:00-9:20. The exam will test your understanding of material from Chapters 1 and 2. For this exam, a well-prepared student should should be able to

    For the exam, you can bring a calculator and formulas on a 3 inch by 5 inch notecard.

    Monday, September 24

    Topics: questions on Section 2.4 homework; a bit about cause-and-effect
    Text: Sections 2.4, 2.5
    Tomorrow: review

    To separate data by a categorical variable in Minitab, use Data: Unstack Columns....

    I've looked for more details on the meaning of the distance variable in the data in Table 2.7 for Exercise 2.82. The endnote references a multimedia statistics "textbook" called ActivStats. This product includes the software described in the problem. I could not find specific details about the distance variable so I'm still a little confused.

    If you want to play with a set-up similar to the one described in Exercise 2.82, try this applet. The distance measured in this experiment is the distance between the center (or centre) of the current target and the click location. This distance measures how the accuracy of the click. This differs from how we came to interpret the meaning of distance in the Table 2.7 data.

    Exam #1 will be on Thursday from 8:00-9:20 am. The exam will test your understanding of material from Chapters 1 and 2.

    Friday, September 21

    Topics: more on regression lines
    Text: Sections 2.3, 2.4
    Tomorrow: using correlation and regression carefully

    You should read Section 2.4 and work on the assigned exercises. We'll clarify the ideas in Section 2.4 in class on Monday by discussing questions you bring from the reading and homework.

    One idea introducing in Section 2.4 is a residual plot. Exercise 2.63 calls for you to make a residual plot. You should do this by hand to make sure you understand what a residual plot is all about. After that, you can use computing technology to make other residual plots. In Minitab, go to Stat: Regression: Filled Line Plot.... Fill in the Response and Predictor (i.e., explanatory) variables as usual. Then click the Graphs... button. In the box Residuals versus the variables:, enter the Predictor (explanatory) variable. Hit OK and then OK again on the main dialog box. Minitab should produce two plots: the scatterplot of response variable vs. explanatory variable with the regression line included and the scatterplot of residuals vs. explanatory variable.

    Thursday, September 20

    Topics: questions on Section 2.2 homework; regression lines
    Text: Section 2.3
    Tomorrow: more on regression lines

    In class, we talked about the least-squares regression line for two variables that have some linear association. Our focus was on understanding how to compute and think about the slope and intercept of a least-squares regression line. Tomorrow, we will talk about the idea behind the line. This will explain the least-squares part of least-squares regression line.

    To get a plot and formula for a least-square regression line in Minitab, use Stats:Regression:Fitted Line Plot....

    Tuesday, September 18

    Topics: questions on Section 2.1 homework; correlation
    Text: Section 2.2
    Tomorrow: regression lines

    To get the correlation for two variables in Minitab, use Stat: Basic Statistics: Correlation....

    Quiz #2 will be at the beginning of class (8:30) on Thursday. It will consist of problems taken from homework assignments denoted above. You can use any notes you bring. You should bring a (working!) calculator. I'll supply a table of standard normal probabilities similar to Table A from the inside front cover.

    In class, we speculated on what actually went on in the study summarized in Exercise 2.9 on "social distress" and branin activity. Here's a fuller description from the original source:

    fMRI scans were acquired while participants played a virtual ball-tossing game ("CyberBall") with what they believed to be two other players, also in fMRI scanners, during which the players eventually excluded the participant (21). In reality, there were no other players; participants were playing with a preset computer program and were given a cover story to ensure that they believed the other players were real (22).

    In the first scan (ISE), the participant watched the other "players" play Cyber-Ball. Participants were told that, because of technical difficulties, the link to the other two scanners could not yet be made and thus, at first, they would be able to watch but not play with the other two players. This cover story was intended to allow participants to view a scene visually identical to ESE without participants believing they were being excluded. In the second scan (inclusion), participants played with the other two players. In the final scan (ESE), participants received seven throws and were then excluded when the two players stopped throwing participants the ball for the remainder of the scan (~45 throws). Afterward, participants filled out questionnaires assessing how excluded they felt and their level of social distress during the ESE scan (22).

    It doesn't sound as traumatic as we were perhaps imagining. You can access an electronic version of the full original source through our library's full-text databases. The reference is "Does rejection hurt? An fMRI study of social exclusion" Naomi I Eisenberger, Matthew D Lieberman, Kipling D Williams. Science. Washington: Oct 10, 2003. Vol. 302, Iss. 5643; p. 290. A fast way to get started is through the Journal Locator link on the library main page. A search for the journal Science will bring up several options. I used the ProQuest Research Library database.

    Monday, September 17

    Topics: questions on Section 1.3 homework; associations among variables; scatterplots; starting in on correlation
    Text: Sections 2.1, 2.2
    Tomorrow: correlation

    For Exercise 2.13, you are asked to make a scatterplot that distinguishes points for male and female individuals. To do this in Minitab, you'll need a data file with a column for sex in addition to the columns for mass and rate. In Minitab, go to Graph: Scatterplot.... In the first dialog box, change to With Groups from the default of Simple. In the following dialog box, set up Y variables and X variables as usual. Then, enter sex in the box labeled Categorical variables for grouping (0-3):.

    Friday, September 14

    Topics: questions on Section 1.3 homework; variables v. values; more on standardizing values; normal quantile plots as a test for normality
    Text: Section 1.3
    Tomorrow: relationships among variables

    A Probability Plot in Minitab serves the same purpose as a normal quantile plot as described in the text. The default format for probability plots in Minitab differs from what the text uses in three ways:

    You can use the Minitab default. The central question remains the same: To what degree do the points fall along a straight line? The more the points fall along the line, the more closer the distribution is to being normal. With the Minitab default, granularity will show up as points lined up vertically. With the text's choices, granularity will show up as points lined up horizontally. You don't need to worry about the precise meaning of the 95% confidence interval curves. You can use these in making a judgment about normality. If most of the points fall within the curves, assuming normality is probably fine.

    Here's steps you can take to have Minitab produce a plot in the same style as the text:

    If you want to get rid of the confidence interval curves, go to Distribution... on the main dialog box (next to the Scale... button you used above). Go to the Data Display tab and uncheck Show confidence intervals.

    Thursday, September 13

    Topics: Quiz #1; questions on Section 1.3 homework; computing proportions for normal distributions
    Text: Section 1.3
    Tomorrow: testing the normality of a distribution

    Minitab tip: In class a few days ago, we looked at the variable Height from the Fall 2007 Math 160 Survey. To separate data for females and males, I manually copied and pasted. You can automate this using \Data\Unstack Columns....

    Tuesday, September 11

    Topics: questions on Section 1.3 homework; shapes of normal density curves; the 68-95-99.7 rule
    Text: Section 1.3
    Tomorrow: Quiz #1; still more on normal density curves

    On Thursday, we will start the hour with Quiz #1. The quiz will consist of several problems taken from the homework assignments for Sections 1.1 and 1.2, and the first assignment for Section 1.3. You'll have ten minutes for the quiz. You can use a calculator to do arithmetic.

    In class, we looked at one variable from the Fall 2007 Math 160 survey. All of the data from the survey is available on Alexandria in file \stats\Jackson\Data\Survey\M160F07Rev.MTW

    I don't have a specific office hour scheduled for Wednesdays but I am generally available most of the day except between noon and 2 pm. Stop by, call, or e-mail if you have questions or want to talk.

    Monday, September 10

    Topics: questions on Section 1.2 homework; density curves; uniform density curves; introduction to normal density curves
    Text: Section 1.3
    Tomorrow: more on normal density curves

    Friday, September 7

    Topics: questions on Section 1.1 homework; standard deviation; practice with Minitab
    Text: Section 1.2
    Tomorrow: density curves; normal distributions

    Here's a brief reminder on how to get to Minitab versions of the text's data from examples, exercises, and tables:

    Everyone on campus has their own share on Alexandria. To access your share, follow the instructions above but use your login name in place of stats. You can use your share on Alexandria to make a backup copy of files from your own computer. It's also a good place to save your files when you are working on a university computer. You can then access your files from any other computer on the university network. For the OIS instruction sheet on connecting to Alexandria, go to OIS infosheets.

    Thursday, September 6

    Topics: histograms; numerical descriptions of a distribution; five-number summary; boxplots
    Text: Section 1.2
    Tomorrow: variance and standard deviation; hands-on with Minitab

    Tomorrow, Friday September 7, we will meet in the McIntyre 324 computer lab so you can get some experience using Minitab. I also plan to spend some time addressing questions from homework.

    I think I have fixed the problem that prevented you from opening the link to the Minitab version of the data from Table 1.9 in the previous Daily Note. Try it again. Let me know if it doesn't work.

    I've assigned a few problems from Section 1.2. I'll assign more problems from this section tomorrow after we've talked about standard deviation and you've gotten some experience with Minitab.

    Tuesday, September 4

    Topics: course logistics; first look at data; stemplots; Minitab demo
    Text: Section 1.1
    Tomorrow: more on initial exploration of data

    Read Section 1.1. Most of this is descriptive. You should become familiar with the terminology introduced in this section. We will not go through all of this terminology systematically in class. We will use the terminology in class. Ask for clarification if we use words in class and you're not clear on the precise meaning.

    Try your hand at the assigned problems. The last three problems involve a larger data set so you'll probably want to use computing technology, such as Minitab, for these. Minitab should be available in the Library Commons, Library 034, McIntyre 324, and Thompson 177/189.

    Rather than entering all of the data for the last three problems into Minitab by hand, you can download a data file:
    Table 1.9 in Minitab Portable format.
    After you download this file, go to Edit: Open Worksheet... in Minitab. In the dialog box that opens, you'll need to use the pull-down menu for Files of type: and select Minitab Portable (*.mtp).

    Try to get started on Minitab, but don't worry if you don't get too far. We'll talk more about using Minitab in class on Thursday. I'll show you how to download data for any of the text's examples and exercises. (If you want to explore downloaded data on your own, follow the textbook link below.)

    Useful Class Links

    Course Project

  • Course Project Warm-up 1 Due Friday, October 5
  • Course Project Warm-up 2 Due Friday, November 2
  • Course Project Warm-up 3 Due Tuesday, November 13
  • Course Project Warm-up 4 Due Tuesday, November 20
  • Fun Stuff

    Check out the Astronomy Picture of the Day.