MATH 450: Mathematical Statisticsvucdinh.github.io/Files/lecture1.pdf · Textbook: Modern...

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MATH 450: Mathematical Statistics

Vu Dinh

Departments of Mathematical SciencesUniversity of Delaware

August 29th, 2017

Vu Dinh MATH 450: Mathematical Statistics

General information

Classes:Tuesday & Thursday 9:30-10:45 am, Gore Hall 115

Office hours:

Tuesday 1-2 pm, Ewing Hall 312.Wednesday 11am-12pm, Ewing Hall 312.

Website: http://vucdinh.github.io/m450f17

Textbook: Modern mathematical statistics with applications(Second Edition). Devore and Berk. Springer, 2012.

Vu Dinh MATH 450: Mathematical Statistics

Evaluation

Overall scores will be computed as follows:25% homework, 10% quizzes, 25% midterm, 40% final

No letter grades will be given for homework, midterm, or final.Your letter grade for the course will be based on your overallscore.

The two lowest homework scores and the lowest quiz scorewill be dropped.

Here are the letter grades you can achieve according to youroverall score.

≥ 90%: At least A≥ 75%: At least B≥ 60%: At least C≥ 50%: At least D

Vu Dinh MATH 450: Mathematical Statistics

Homework

Vu Dinh MATH 450: Mathematical Statistics

Homework

Assignments will be posted on the website every otherTuesday (starting from the first week) and will be due onThursday of the following week, at the beginning of lecture.

No late homework will be accepted.

Two lowest homework scores will be dropped in thecalculation of your overall homework grade.

Vu Dinh MATH 450: Mathematical Statistics

Quizzes and exams

At the end of every chapter, there will be a short, multiplechoice quiz during class.

The quiz dates will be announced at least one class inadvance.

The lowest quiz score will be dropped.

There will be a midterm on 10/26 and a final exam duringexams week.

Vu Dinh MATH 450: Mathematical Statistics

Data analysis

Open source statistical system R

http://cran.r-project.org/

Vu Dinh MATH 450: Mathematical Statistics

Tentative schedule

Vu Dinh MATH 450: Mathematical Statistics

About me

PDEsmathematical financeuncertainty quantificationexperimental designcomputational biologystatistical machine learning

Vu Dinh MATH 450: Mathematical Statistics

Topics

Textbook: Modern mathematical statistics with applications(Second Edition).Devore and Berk. Springer, 2012.

Week 1 · · · · · ·• Chapter 1: Descriptive statistics

Week 2 · · · · · ·• Chapter 6: Statistics and SamplingDistributions

Week 4 · · · · · ·• Chapter 7: Point Estimation

Week 7 · · · · · ·• Chapter 8: Confidence Intervals

Week 10 · · · · · ·• Chapter 9: Test of Hypothesis

Week 13 · · · · · ·• Two-sample inference, ANOVA, regression

Vu Dinh MATH 450: Mathematical Statistics

Chapter 1: Overview and Descriptive Statistics

Vu Dinh MATH 450: Mathematical Statistics

Living in a world of uncertainties

— Insanity is doing the same thing over and over and expecting adifferent result

Vu Dinh MATH 450: Mathematical Statistics

Modeling uncertainty and randomness

probability → random variables

numerical analysis → uncertainty quantification

electrical engineer → fuzzy logic

theory of evidence, possibility theory

Vu Dinh MATH 450: Mathematical Statistics

Random variable

Vu Dinh MATH 450: Mathematical Statistics

What do we want?

make meaningful statement about the uncertain world(e.g.: Smoking is bad for your health)

saying those statements with confidence(e.g.: I’m 95% sure that smoking is bad for health)

quantify uncertainties

making prediction about uncertain outcomes(I’m 90% sure that the McDonald’s stock is rising)(The weather channel says there is a 90% that it will rain)

using such predictions for our personal gains(I’m bringing an umbrella with me today)

Vu Dinh MATH 450: Mathematical Statistics

Is it even possible to do so?

The law of large numbers (Chapter 6)

The Central Limit Theorem (Chapter 6)

Asymptotic normality of the maximum likelihood estimator(Chapter 7)

Vu Dinh MATH 450: Mathematical Statistics

How are we going to do it?

Vu Dinh MATH 450: Mathematical Statistics

How are we going to do it?

population: a well-defined collection of objects of interest

when desired information is available for all objects in thepopulation, we have what is called a census→ very expensive

a sample, a subset of the population, is selected→ we obtain a data set → make prediction/test hypothesis

Vu Dinh MATH 450: Mathematical Statistics

Chapter 1: Descriptive Statistics

Goal: describe a data set

By pictures and tables (1.2)

By measures of locations (1.3) and variability (1.4)

Vu Dinh MATH 450: Mathematical Statistics

Pictorial and Tabular Methods

Stem-and-Leaf displays

Dotplots

Histograms

Vu Dinh MATH 450: Mathematical Statistics

Stem-and-Leaf displays

44 46 47 49 63 64 66 68 6872 72 75 76 81 84 88 106

Vu Dinh MATH 450: Mathematical Statistics

Dotplots

Vu Dinh MATH 450: Mathematical Statistics

Histograms

Vu Dinh MATH 450: Mathematical Statistics

Histograms: unequaled class width

Vu Dinh MATH 450: Mathematical Statistics

Measures of locations: mean

Vu Dinh MATH 450: Mathematical Statistics

Measures of locations: median

Step 1: ordering the observations from smallest to largest

Vu Dinh MATH 450: Mathematical Statistics

Measures of locations: median

Data set

15.2, 9.3, 7.6, 11.9, 10.4, 9.7, 20.4, 9.4, 11.5, 16.2, 9.4, 8.3

Ordered list

7.6, 8.3, 9.3, 9.4, 9.4, 9.7, 10.4, 11.5, 11.9, 15.2, 16.2, 20.4

Median =9.7 + 10.4

2= 10.05

→ Median is not affected by outliers

Vu Dinh MATH 450: Mathematical Statistics

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