Outbreak Investigations
Paul Hsu, MPH, Ph.D.
Department of Epidemiology
UCLA Fielding School of Public Health
1
Mickey and Me(asles)
12 cases as of 1/8, 26 as of 1/13 (22 in CA, 4 in Utah,
Colorado, Washington).
2014 worst for measles in CA since 1995
(
Epi 100
Worksheet 3 Mortality
Table 1: Data from City Y
Estimated Population
Total # of males
Total # of females
Total # of mothers
Total # of deaths
Deaths from breast cancer
Total # live births
# infant deaths (< 1 yr. of age)
# fetal deaths (>22 weeks
EPI100
Worksheet #1
Introduction to Epidemiology
1. What is epidemiology?
the study of the distribution and determinants of healthrelated states or events in
specified populations and the application of this study to control of health problems.
Gordis p.
EPI 100
Worksheet 4  Standardization
1. What is the purpose of standardization?
Standardization allows for the comparison of disease or mortality rates between populations with
different distributions of factors related to disease occurrence, such as age
EPI100
Worksheet #1
Introduction to Epidemiology
1. What is epidemiology?
the study of the distribution and determinants of healthrelated states or events in
specified populations and the application of this study to control of health problems.
Gordis p.
Epi 100, Summer 2015
HOMEWORK #1 KEY
TRUE/FALSE (circle T or F)
T
F
The incubation period is the time from onset of signs and symptoms until a cure is achieved.
T
F
Active immunity means that a mother actively passes antibodies to her offspring during pre
EPI100,Summer2015
HOMEWORK#2: Due July 27th by 12pm
1. You decide to test a new method for diagnosing legionella using 500 urine samples. Based on the gold
standard test, 125 of the 500 urine samples truly have disease. With the new screening, 85 urine s
CrossSectional
and Ecologic Studies
Paul Hsu, MPH, PhD
Department of Epidemiology
UCLA Fielding School of Public Health
1
Introduction
A study where exposure and disease are
determined at the same time (a snapshot or
crosssection).
Usually conducted a
CaseControl Studies
Paul Hsu, MPH, PhD
Department of Epidemiology
UCLA Fielding School of Public Health
Introduction
Cases: persons with a specific disease (or
other outcome)
Controls: persons without the disease.
Casecontrol study: information is ob
EPI100
Worksheet #1
Introduction to Epidemiology
1. What is epidemiology?
the study of the distribution and determinants of healthrelated states or events in
specified populations and the application of this study to control of health problems.
Gordis p.
Experimental Studies
Paul Hsu, MPH, PhD
Department of Epidemiology
UCLA Fielding School of Public Health
1
I. Introduction
Defined:
a study design in which the investigator
actively controls who is exposed and who is
not. Ideally, subjects are randomly a
EPI100
Worksheet 2
Incidence and Prevalence
1. Indicate whether each of the following is a measure of incidence or prevalence.
A. Number of adults in the United States who currently suffer from arthritis
Prevalence
Gordis 5E p. 4651
B. Percentage of UCLA
Epi 100
Worksheet 3 Mortality
Table 1: Data from City Y
Estimated Population
Total # of males
Total # of females
Total # of mothers
Total # of deaths
Deaths from breast cancer
Total # live births
# infant deaths (< 1 yr. of age)
# fetal deaths (>22 weeks
Epi 100
Worksheet 5: Screening
1. Using the terminology in the table, what are
the two measures of validity of a screening
test and how would you calculate them?
TRUTH
TEST
+

Disease
A (TP)
C (FN)
No Disease
B (FP)
D (TN)
Sensitivity: The proportion of
EPI 100
Worksheet 4  Standardization
1. What is the purpose of standardization?
Standardization allows for the comparison of disease or mortality rates between populations with
different distributions of factors related to disease occurrence, such as age
Winter2015
EPI 100
Worksheet 6
Predictive Value of a Test and Reliability
TRUTH
TEST
+
Total
Disease
A (TP)
C (FN)
A+C
No Disease
B (FP)
D (TN)
B+D
Total
A+B
C+D
A+B+C+D
1. What does the positive predictive value (PPV) of a test measure?
The proportion of
Epidemiology 100
Winter 2015
Worksheet 09 Case Control Studies
1. What is an Odds Ratio (OR)? How
does the definition of the OR differ for
cohort vs. casecontrol studies? How
do we interpret an OR?
Exposed
Unexposed
Total
Disease
a
c
a+c
No Disease
b
d
b
Hsu: Epi 100
Worksheet 3 Mortality
Table 1: Data from City Y
Estimated Population
Total # of males
Total # of females
Total # of mothers
Total # of deaths
Deaths from breast cancer
Total # live births
# infant deaths (< 1 yr. of age)
# fetal deaths (>22 w
Cohort Studies
Paul Hsu, MPH, PhD
Department of Epidemiology
UCLA Fielding School of Public Health
Introduction
Cohort: a group who shares a common exposure
or experience within a defined time period
Cohort study: persons free of disease or outcome
divi
The Natural History of Disease:
Prognosis
Gordis, Chapter 6
Paul Hsu,MPH, PhD
Department of Epidemiology
UCLA Fielding School of Public Health
Prognosis
Definitions:
a prediction of the probable course and
outcome of a disease
the likelihood of recover
Epi 100, Summer 2015
HOMEWORK #1 KEY
TRUE/FALSE (circle T or F)
T
F
The incubation period is the time from onset of signs and symptoms until a cure is achieved.
T
F
Active immunity means that a mother actively passes antibodies to her offspring during pre
Hsu: Epi 100
Worksheet 09 Case Control Studies
1. What is an Odds Ratio (OR)? How
does the definition of the OR differ for
cohort vs. casecontrol studies? How
do we interpret an OR?
Exposed
Unexposed
Total
Disease
a
c
a+c
No Disease
b
d
b+d
Total
a+b
c+d
CH20. INTRODUCTION TO REGRESSION MODELS
REGRESSION FUNCTIONS
REGRESSION of a variable Y on another variable X = function that describes how the mean value of Y
changes across population subgroups defined by values of X.
E(YX=x) : the average of Y when th
1) Review
a) Cohort vs. CaseControl
b) Generalized linear model
c) DAGs
2) DAGs
a) Overadjustment vs. Unnecessary adjustment
b) Berksonian bias & missing data (MAR, MCAR)
3) Statistical Inference
a) DAGs for measurement errors
b) Statistical inference
i
EPI 200A
Guest Lectures
L13. Behavioral Epidemiology
Definition
o Study of the distribution and etiology of healthrelated behaviors in population
Issues
o Definition
o Timeframe
o Emotion
o Judgment
o Consequence
Study process
o Existing data
o Making
200A Midterm Final Thoughts:
To answer the question about relationship between Risk, Rate, and Odds:
Reference: pgs 60 & 61 of ME3
Nonratio measures:
o All three measures will be approximately equal when risk is small and the risk only declines slightly
CH13. Fundamentals of Epidemiologic Data Analysis
Methods used to estimate the proportion of population with a disease
Name
Formula
Assumptions
Combinatorial/Binomial
N!
N =
coefficient
y
y ! ( N y )!
( )
Binomial distribution
(Exact statistics)
NN
has
y
Fundamentals of Epidemiologic Data Analysis
Methods used to estimate the proportion of population with a disease.
Combinatorial/Binomial
N!
N =
coefficient
y
y ! ( N y )!
( )
Binomial distribution
(Exact statistics)
:N
N y has to be very large.
Pr ( Y =