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Investigations for Introducing Mathematically Inclined Students to Statistics

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Investigations for Introducing Mathematically Inclined Students to Statistics

Allan Rossman(arossman@calpoly.edu)

Beth Chance (bchance@calpoly.edu)

- Introductory statistics course for mathematically inclined students
- mathematics and statistics majors
- future secondary teachers
- perhaps strong science, engineering, computer science majors

- Brainstorm your goals for these students, particularly with attention to whether and how these goals differ from service courses (5 min)
- Reporter summarize top three goals

- Supplement with data analysis component
- Witmer’s Data Analysis: An Introduction

- Infuse data and applications
- Rice’s Mathematical Statistics and Data Analysis

- Use lab activities
- Nolan and Speed’s StatLabs
- Baglivo’s Mathematica Laboratories for Mathematical Statistics

To develop and provide a:

Data-Oriented, Active Learning, Post-Calculus

Introduction to Statistical

Concepts, Applications, Theory

Supported by the NSF DUE/CCLI #9950476, 0321973

- Put students in the role of active investigator
- Motivate with real studies, genuine data
- Emphasize connections among study design, inference technique, scope of conclusions
- Use simulations frequently
- Use a variety of computational tools
- Investigate mathematical underpinnings
- Introduce probability “just in time”
- Experience entire statistical process over and over
- Provide a combination of immediate corrective formative and summative evaluation of key concepts

Outline

- Full versions available at www.rossmanchance.com/iscam/uscots/
- Investigation 1: Sleep Deprivation and Visual Learning (randomization tests)
- Investigation 2: Sampling Words (random samples, variability)
- Investigation 3: Kissing the Right Way (confidence intervals)
- Investigation 4: Sleepless Drivers (CI for Odds Ratio)

- Physiology Experiment
- Stickgold, James, and Hobson (2000) studied the long-term effects of sleep deprivation on a visual discrimination task

(3 days later!)

sleep condition n Mean StDev Median IQR

deprived 11 3.90 12.17 4.50 20.7

unrestricted 10 19.82 14.73 16.55 19.53

- How often would such an extreme experimental difference occur by chance, if there was no sleep deprivation effect?
- Set of 21 index cards with the improvement scores (positive and negative).
- Randomly assign 11 of the cards to the sleep deprived group.
- Calculate the difference in group means(deprived – unrestricted)

- After this reminder of the randomization process, students then use a Minitab macro
sample 21 c2 c3

unstack c1 c4 c5;

subs c3.

let c6(k1)=mean(c4)-mean(c5)

let k1=k1+1

15.92

- Students investigate this question through
- Hands-on simulation (index cards)
- Computer simulation (Minitab)
- Exact distribution

p-value=.0072

p-value .002

- Experience the entire statistical process again
- Develop deeper understanding of key ideas (randomization, significance, p-value)
- Effect of variability

- Tools change, but reasoning remains same
- Tools based on research study, question – not for their own sake

- Simulation as a problem solving tool
- Empirical vs. exact p-values

Four score and seven years ago, our fathers brought forth upon this continent a new nation: conceived in liberty, and dedicated to the proposition that all men are created equal.

Now we are engaged in a great civil war, testing whether that nation, or any nation so conceived and so dedicated, can long endure. We are met on a great battlefield of that war.

We have come to dedicate a portion of that field as a final resting place for those who here gave their lives that that nation might live. It is altogether fitting and proper that we should do this.

But, in a larger sense, we cannot dedicate, we cannot consecrate, we cannot hallow this ground. The brave men, living and dead, who struggled here have consecrated it, far above our poor power to add or detract. The world will little note, nor long remember, what we say here, but it can never forget what they did here.

It is for us the living, rather, to be dedicated here to the unfinished work which they who fought here have thus far so nobly advanced. It is rather for us to be here dedicated to the great task remaining before us, that from these honored dead we take increased devotion to that cause for which they gave the last full measure of devotion, that we here highly resolve that these dead shall not have died in vain, that this nation, under God, shall have a new birth of freedom, and that government of the people, by the people, for the people, shall not perish from the earth.

- Examine the average length of words in the sample

The population mean of all 268 words is 4.295 letters

- Students use Minitab to select sample and compare results
- Example results

- Then turn to technology (applet)
- What is the long-term behavior of this (random) sampling method?
- Unbiased method?

- What happens if we change sample size? Population size?

- What is the long-term behavior of this (random) sampling method?

- Using various forms of technology to support student conceptual learning
- Tailored to the context
- Dynamic, interactive, and visual
- Easy to use

- Confront most common student misconceptions directly
- Distinguish randomization from random sampling

- Biopsychology observational study
- Güntürkün (2003) recorded the direction turned by kissing couples to see if there was also a right-sided dominance.

- Is 1/2 a plausible value for p, the probability a kissing couple turns right?
- Binomial Simulation applet
- Introduce idea of two-sided p-value

- Is 2/3 a plausible value for p, the probability a kissing couple turns right?
- Discuss calculation of non-symmetric two-sided p-values

- Have students explore and develop an “interval” of plausible values for p

- Use another applet to explore the meaning of confidence level
- Wald vs. adjusted Wald
- z vs. t
- Robustness of t-intervals

- Encourage students to make predictions and test their knowledge
- Use the technology to minimize computational burden so students focus on concepts
- Return to key ideas often, increasing the level of complexity each time
- Give them a taste for the modern flavor of statistical practice and methodology

- Sociology case-control study
- Connor et al (2002) investigated whether those in recent car accidents had been more sleep deprived than a control group of drivers

- Sample proportion that were in a car crash
- Sleep deprived: .581
- Not sleep deprived: .466

Odds ratio: 1.59

- How often would such an extreme observed odds ratio occur by chance, if there was no sleep deprivation effect?

1.59

- Students investigate this question through
- Computer simulation (Minitab)
- Empirical sampling distribution of odds-ratio
- Empirical p-value

- Approximate mathematical model

- Computer simulation (Minitab)

- SE(log-odds) =
- Confidence interval for population log odds:
- sample log-odds +z* SE(log-odds)
- Back-transformation

- 90% CI for odds ratio: 1.13 – 2.24

- Students understand process through which they can investigate statistical ideas
- Students piece together powerful statistical tools learned throughout the course to derive new (to them) procedures
- Concepts, applications, methods, theory

- Issues in sampling, nonsampling errors
- Understand the implications of improper sampling
- Analyze data numerically and graphically, communicate their results
- Be able to explain how random variability affects the conclusions we should draw
- Verbalize student conclusions that follow based on study design – Causation? Generalizability?
- Explain the idea behind randomization/sampling distributions, think statistically
- Increasing understanding of confidence, p-value

- Are these worthy goals?
- Recruiting students into statistics (2nd course…)
- Preparing future teachers

- Is such a course feasible?
- Learning environment
- Course structure
- Integration of technology

- What are the essential components in students’ ability and understanding to assess?

- Applets, data files, other resources:
www.rossmanchance.com/iscam/

- Faculty development workshop (July 18-22, 2005):
www.rossmanchance.com/prep/workshop.html

- Review copies of text:
www.duxbury.com

- Allan Rossman (arossman@calpoly.edu)
- Beth Chance (bchance@calpoly.edu)