Practice problems for Exam I - P6103F10
1) A patient has been stuck with a needle that is infected with Hepatitis B. His doctor wants to know the
probability that this patient will actually develop the disease. The doctor looks at previous studies and fin

Population & Samples
Population:
The entire group of individuals or items, with
common characteristics, that we want to study.
- target population: subjects desired to be studied
- sampled population: subject studied
Sample:
A part of the population from

P6103
Introduction to Biostatistics
09/08/10 - Lecture 1
1
Outline
Introduction
Syllabus
Structure of the course
Principle of statistics
Sampling
Classication of study design
Observational Study, Experiment
2
What is Statistics ?
Statistics is a el

EHS Lecture 7 Study Guide
Spring 2012
Lecture 7: Surface water and ground water contamination
Surface water contamination: Dr. LeBlancq
Know the definitions of infectious disease and microbes.
o The essential feature of most infections is the successful m

EHS Lecture 4 Study Guide
Spring 2012
Lecture 4: Environmental Risk Assessment
What is risk?
Risk: is the likelihood that harm will actually be done by the realization of the hazard
during the work being carried out or by the way something is used.
Risk

EHS Lecture 3 Study Guide
Spring 2012
Lecture 3: Exposure Assessment, UV, Ozone and Skin Cancer
How does formaldehyde occur in the environment? How are we exposed?
What are the health effects and why do they differ between people?
Cigarette smoke, automob

Identify the type of variables
Maker of the car driven by (random) subjects
qualitative - nominal variable
Number of pets in subjects household
quantitative - discrete variable
Length of subjects femur (in cm)
quantitative - continuous variable
Arm

Type of studies and sampling
P6103
Introduction to Biostatistics
09/20/10 - Lecture 4
Hey, Pops, what was that letter you sent off to Ann
Landers yesterday?
4
Monday, September 20, 2010
1
Monday, September 20, 2010
4
Review question 2
Outline
Problem:
In

Exam I
Auditorium 8th oor
The exam starts SHARP on time!
P6103
Introduction to Biostatistics
What to bring:
Pen, pencil, eraser
Calculator
1 sheet (11x8 in) of notes (both side)
non-aromatic drink or food (if desired)
picture ID !
10/13/10 - Lecture

Sampling distributions
The roll on a single die is a discrete random variable. What
is its distribution?
X = roll on 1 die Y = avg of 2 dice Z=avg of 3 dice
P6103
Introduction to Biostatistics
10/11/10 - Lecture 10
1
2
3
4
5
6
1 1.5 2 2.5 3 3.5 4 4.5 5 5.

Review problem I
The sodium level in healthy individuals has appr. normal
dist. with mean of 141.5 mEq/l and SD of 3.25 mEq/l
Find the proportion of the healthy population with sodium
level higher than 145 mEq/l?
Sodium levels . X ~ N( =141.5, ! = 3.25!)

Problem continued:
X = number of new patients who need some dentistry
work done
X ~ Bi (n=5, p=.6)
The dentists loyal assistant counted the number of new
patients needing some work in the next 150 days. He
found out that on 2 days no patient had work done

Binomial Distribution
n=10
p=.5
n=20
p=.5
n=10
p=.1
n=20
p=.3
P6103
Introduction to Biostatistics
09/29/10 - Lecture 7
Wednesday, September 29, 2010
1
Wednesday, September 29, 2010
4
Binomial Distribution Rules
Outline
A random variable (r.v.) X is said t

Review problem about mice
Review problem: Mothers on Valium spanking their children
Review problem about wooden floors
Review Problem: Clinical trial with completers and 3 sites
Review problem:
Bayes Theorem
Blond student

Example:
A population of 2000 new born mice was 40% males. Out of all
new born mice, 30% were healthy males. All together, there
were 500 mice who were diseased.
Are events M = male mouse and H=Healthy independent?
P6103
Introduction to Biostatistics
Give

Set Theory
A complement of an event A is a set of all outcomes in the sample
space which are not in A. It is denoted A.
An intersection of two events, A and B, is another event which
contains outcomes which belongs to event A and also to event B.
P6103
In

EHS Lecture 1 Study Guide
Spring 2012
Lecture 1: Introduction to EHS
Know some of the evidence that global warming is happening and what actions
governments/UN have taken.
Evidence: Glacial recession; Rising ocean levels (more than average over past 1000

P6103 Syllabus
Fall 2010
P6103 - Introduction to Biostatistics
COURSE DESCRIPTION
Biostatistics is essential to ensuring that findings and practices in public health and biomedicine are
supported by reliable evidence. This course covers the basic tools fo

ANOVA
Example:
Researchers want to evaluate the effect of exercise on
overall health. They randomly sample 500 subjects, split
them into categories, and test their overall health with a
lengthy questionnaire which was summarized by a total
score (0=dead,

Solution (twins)
Step I: Establish statistical hypothesis
Step II: Test statistic
P6103
Introduction to Biostatistics
Step III: p- value
p-value = P(T > 4.21) is smaller than .005 thus smaller
than .05 (level of signicance), so we reject null hypothesis
S

2 groups proportions CI
summary slide :)
CLT assumptions:
P6103
Introduction to Biostatistics
(1- !)% CI:
11/08/10 - Lecture 18
1
4
Monday, November 8, 2010
1
Monday, November 8, 2010
4
2 groups CI - proportions
Outline
Example Color blindness study:
In a

Type I Error
Type I Error is dened as the event of wrongly rejecting Ho, i.e.
accepting H1 when in reality Ho is true!
(innocent subject goes to jail)
P6103
Introduction to Biostatistics
P(Type I Error) = P(Ho rejected | Ho true) = !
11/03/10 - Lecture 17

Panda Bears problem
Example: It is known from the literature that the head
circumference mean and standard deviation of wild born
panda bears is 40 cm and 2 cm.
P6103
Introduction to Biostatistics
In order to test the claim that the mean head
circumferenc

Proportion CI - last review
(a) Find a point estimate for p= proportion of neutrophils
(b) Find an inter val estimate for p (with 90% condence)
P6103
Introduction to Biostatistics
10/27/10 - Lecture 15
(c) In a normally healthy individual,the percentage o

P6103
Introduction to Biostatistics
10/25/10 - Lecture 14
4
1
Monday, October 25, 2010
1
Monday, October 25, 2010
4
Student t-distribution k df
Outline
With (1-alpha) condence, we can estimate that the
population mean is within the interval:
Review
Chapte

ANOVA
Ho: There are no differences vs. Ha: there are differences
Ho: ne = ole = ohe = r1e = r2e vs. Ha: not Ho
P6103
Introduction to Biostatistics
11/24/10 - Lecture 23
In ANOVA we compute the test statistic as:
The larger the F, the more likely we reject