Inference
Jenises STA103
Probability/Statistical contact info
Instructor: Jenise Swall Office: 221 Old Chem Bldg. Phone: [phone] Office hours: Wed. 9:30PM-10:30PM, Thu. 1:30PM-2:30PM [e-mail]
TA contact info
Christine KohnenMickelson Office: 212 Old Chem Bldg. Phone: [phone] Office hours: TBA [e-mail] Tao Jiang (Tom) Office hours: TBA [e-mail]
Overview
Covers skills needed for further study in econ or quantitative social science Much more mathematically-intensive than STA101 or STA102 You must be familiar with calculus at least at the level of MTH31 Practice is essential expect to put in many extra hours outside of class
Topics
First part of course: probability concepts
Basics, conditional probability, Bayes theorem Discrete and continuous random variables Joint distributions
Second part of course: statistical concepts
Estimators, sampling distributions, bias Confidence intervals, hypothesis testing Maximum likelihood estimation Regression
CourseInfo page
Course web page is primary reference point for schedules, assignments, etc. CourseInfo system used to maintain the site and provide security so you can view your grades online You must be enrolled in STA103 to make full use of the CourseInfo page
Using CourseInfo
First, obtain your CourseInfo userid and password. Detailed instructions are on the public STA103 page: www.stat.duke.edu/courses/Spring01/sta103 Relevant info will be on both pages until add/drop ends, for the convenience of those waitlisted.
Course materials
Required text: Mathematical Statistics with Applications by Wackerly, Mendenhall, Scheaffer (5th edition) Optional text: Student solutions manual for the textbook Calculator capable of logs, exponentiation, powers, etc. for quizzes/exams
Sections
Supervised by TAs Quizzes administered each week Some computer exercises will be incorporated, mostly in the last portion of the course (using S-Plus software) If you need to switch sections, please see me or send me an email
Quizzes
Quizzes administered weekly, but may be cumulative in nature Students must take quizzes in their assigned sections Lowest quiz grade will be dropped (can be used as one unexcused absence)
Exams
Final scheduled by the Registrar for 04MAY on 9AM-12N Two midterms during regular class hours (tentative dates):
Midterm 1: 13FEB Midterm 2: 29MAR
Quiz/exam regrades
You have 2 weeks after test/quiz date to request a regrade Submit a note detailing the nature of the grading error along with the quiz/exam to your TA Papers submitted for regrade may be examined in their entirety; either net gain or net loss possible
Homework
Suggested problems (and solutions) will be posted on the web as site we go along Intended to help you gauge your progress and review the material Will not be graded
Absences
Deans excuse must be presented to be excused from quizzes or to reschedule exams Athletic team schedules, illness, or other less official excuses will not be accepted in place of a Deans excuse
Descriptive statistics
Statistics that we usually see in the media and other everyday events are descriptive statistics These are just summaries of data They include charts, graphs, summary statistics (mean, standard deviation, etc.), and other such displays
Probability & sampling
Because the population is large, the sample is a useful way of understanding it If we know what the make-up of the population is, then we can calculate the probability of obtaining a certain sample Caution must be exercised when choosing a sampling scheme to avoid bias
Inference
Inferences are the conclusions made about the population after considering the sample Inferences usually concern quantifiable facts that we are interested in about the population (mean, variance, etc.) Since inferences are rarely exactly correct, we also want to estimate how close we can expect ours to be
Probability/inference
Use inference
Population
Sample
Use probability
Simple example
Question of interest: In At Duke, what percentage of students are econ majors? Method 1: Ask each undergraduate about his/her major, tally results, and find the answer Method 2: Ask a sample about their majors, tally results, and make an estimate
All undergraduate students Psych Econ Econ Econ Econ Econ Econ Econ Econ Econ Econ Bio Psych Econ Soc Eco...