DrugEpi 3-1 Associations and the 2x2 Table Module 3 Introduction Content Area: Analytical Epidemiology Essential Question (Generic): Is there an association between the hypothesized cause and the disease? Essential Question (Drug Abuse Specific): Is there an association between the hypothesized cause and drug use? Enduring Epidemiological Understanding: Causal hypotheses can be tested by observing exposures and diseases of people as they go about their daily lives. Information from these observational studies can be used to make and compare rates and identify associations. Synopsis In Module 3, students explore how hypotheses are tested epidemiologically. Students begin to uncover and develop the following epidemiological concepts and skills: the meaning of the term “association;” the need for a control group; uses of the 2x2 table in calculating risks and relative risks; experimental study design; the importance of ethics in human research; observational study designs used in epidemiology; and the strengths and limitations of each design. Lesson 3-1: Associations and the 2x2 Table Lesson 3-2: Experimental Study - Buprenorphine Example Lesson 3-3: An Actual Randomized Controlled Trial
DrugEpi 3-1 Associations and the 2x2 Table Module 3 Introduction Content Area: Analytical Epidemiology Essential Question (Generic): Is there an association.
Dec 25, 2015
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DrugEpi 3-1 Associations and the 2x2 Table
Module 3 IntroductionContent Area: Analytical EpidemiologyEssential Question (Generic): Is there an association between the hypothesized cause and the disease?Essential Question (Drug Abuse Specific): Is there an association between the hypothesized cause and drug use?Enduring Epidemiological Understanding: Causal hypotheses can be tested by observing exposures and diseases of people as they go about their daily lives. Information from these observational studies can be used to make and compare rates and identify associations.
Synopsis
In Module 3, students explore how hypotheses are tested epidemiologically. Students begin to uncover and develop the following epidemiological concepts and skills: the meaning of the term “association;” the need for a control group; uses of the 2x2 table in calculating risks and relative risks; experimental study design; the importance of ethics in human research; observational study designs used in epidemiology; and the strengths and limitations of each design.
Lesson 3-1: Associations and the 2x2 TableLesson 3-2: Experimental Study - Buprenorphine ExampleLesson 3-3: An Actual Randomized Controlled TrialLesson 3-4: Observational Studies of Natural Experiments - Sensation-Seeking ExampleLesson 3-5: Fundamentals of Study DesignLesson 3-6: Study Design Exercises
DrugEpi 3-1 Associations and the 2x2 Table
Module 3 - Analytical Epidemiology
Lesson 3-1 Associations and the 2x2 Table
Content
• Introduction to the concept of “association” • Diagram and explanation of descriptive versus analytical epidemiology and
how each relates to hypothesized associations• Introduction to the 2x2 table and its use in testing hypotheses• Practice in labeling and understanding the 2x2 table with examples of
hypothesized associations
Big Ideas
• An association is when two things “turn up together”• Epidemiologists study associations • Descriptive epidemiology generates hypotheses about associations and
analytical epidemiology tests hypotheses about associations • The 2x2 table is a tool used to express the numbers of people with and
without the exposure and with and without the outcome. In this way it includes controls.
This project is supported by a Science Education Drug Abuse Partnership Award, Grant Number 1R24DA016357-01, from the National Institute on Drug Abuse,
National Institutes of Health.
DrugEpi 3-1 Associations and the 2x2 Table
1. How is this disease distributed?
Health-related conditions and behaviors are not distributed uniformly in a population. They have unique distributions that can be described by how they are distributed in terms of person, place, and time.
2. What hypotheses might explain the distribution of disease?
Clues for formulating hypotheses can be found by observing the way a health-related condition or behavior is distributed in a population.
3. Is there an association between the hypothesized cause and the disease?
Causal hypotheses can be tested by observing exposures and diseases of people as they go about their daily lives. Information from these observational studies can be used to make and compare rates and identify associations.
4. Is the association causal?
Causation is only one explanation for an association between an exposure and a disease. Because observational studies are complicated by factors not controlled by the observer, other explanations also must be considered.
5. What should be done when preventable causes of disease are found?
Policy decisions are based on more than the scientific evidence. Because of competing values - social, economic, ethical, environmental, cultural, and political factors may also be considered.
Essential Questions Enduring Understandings
Where are we?
DrugEpi 3-1 Associations and the 2x2 Table
Association Found Between Coffee and Pancreatic Cancer
… associated with each other
DrugEpi 3-1 Associations and the 2x2 Table
Handout
Association Found Between Coffee and Pancreatic Cancer
DrugEpi 3-1 Associations and the 2x2 Table
What do we mean when we say that there is an association between two things?
Associated
Tied Related
Linked
Things that are associatedare linked in some way that makes them
turn up together.
… associated with each other
DrugEpi 3-1 Associations and the 2x2 Table
Things that are associated are linked in some way that makes them turn up
together.
Things That Turn Up Together
DrugEpi 3-1 Associations and the 2x2 Table
Suicide Higher in Areas with Guns
Smoking Linked to Youth Eating Disorders
Snacks Key to Kids’ TV- Linked Obesity: China Study
Family Meals Are Good for Mental Health
Lack of High School Diploma Tied to US Death
Rate
Study Links
Spanking to
Aggression
Breakfast Each Day May Keep Colds Away
Study Concludes: Movies Influence
Youth Smoking
Study Links Iron
Deficiency to Math
Scores
Kids Who Watch R-Rated Movies More Likely to Drink, Smoke
Pollution Linked with Birth Defects in US Study
Depressed Teens More Likely to Smoke
Things That Turn Up Together
DrugEpi 3-1 Associations and the 2x2 Table
Review - Descriptive Epidemiology
Descriptive epidemiology can generate hypotheses
about associations
Epidemiologic studies that are concerned with characterizing the amount and distribution of health and disease within a population
DrugEpi 3-1 Associations and the 2x2 Table
New Topic - Module 3 is about Analytical Epidemiology
Analytical epidemiology can test hypotheses
about associations
Epidemiologic studies that are concerned with determinants of disease
and the reasons for relatively high or low
frequencies of disease in specific population
subgroups
DrugEpi 3-1 Associations and the 2x2 Table
Hypothesis about
associations
Generate
Descriptive Epidemiology
Test
Analytical Epidemiology
An unproven idea, based on observation or reasoning, that can be supported or refuted through investigation
An educated guess
Hypotheses in epidemiology are statements that suggest associations between an exposure and an outcome
Epidemiology and Associations
(This connects everything)
DrugEpi 3-1 Associations and the 2x2 Table
Hypothesis about
associations
Generate
Descriptive Epidemiology
Test
Analytical Epidemiology
Epidemiology and Associations
(An example)
Describes observations of kids who drink
and smoke “turning up” at R-
rated movies
Hypothesis: Watching R-rated
movies can influence
teenagers to smoke and drink
alcohol
Scientifically studies the association
between teenage drinking and smoking and going to R-rated
movies to test whether the
hypothesis is refuted or supported
DrugEpi 3-1 Associations and the 2x2 Table
The 2x2 table is a tool used to express the numbers of people
with and without the exposure and with and without
the outcome.
The 2x2 Table
DrugEpi 3-1 Associations and the 2x2 Table
A cross-classification of data where categories of one
variable are presented in rows and categories of another variable
are presented in columns.
The simplest contingency table is the 2x2 table
Contingency Table
DrugEpi 3-1 Associations and the 2x2 Table
TotalSmokingNot
Smoking
Watching R-rated movies
Not watching R-rated movies
Exposure
Outcome / Disease
a b
c d
2x2 Table
Are there controls in this
2x2 table?
If yes, where are they?
DrugEpi 3-1 Associations and the 2x2 Table
People who participate in a study and do not have the exposure of interest
People whose results are compared to the group that was exposed.
Control Group
DrugEpi 3-1 Associations and the 2x2 Table
Exposed
Not Exposed
OutcomeNo
Outcome TotalTests hypotheses
Analytic Epidemiology
What is Important to Understand So Far . . .
Analytical Epidemiology / Study Design
Need for an unexposed comparison group
2x2 table can express
relationships between
exposure and outcome
DrugEpi 3-1 Associations and the 2x2 Table
Suicide Higher in Areas with Guns
Smoking Linked to Youth Eating Disorders
Snacks Key to Kids’ TV- Linked Obesity: China Study
Family Meals Are Good for Mental Health
Lack of High School Diploma Tied to US Death
Rate
Study Links
Spanking to
Aggression
Breakfast Each Day May Keep Colds Away
Study Concludes: Movies Influence
Youth Smoking
Study Links Iron
Deficiency to Math
Scores
Kids Who Watch R-Rated Movies More Likely to Drink, Smoke
Pollution Linked with Birth Defects in US Study
Depressed Teens More Likely to Smoke
In the News
DrugEpi 3-1 Associations and the 2x2 Table
Total
a b
dc
2 x 2 Table
Suicide Higher in Areas with Guns
DrugEpi 3-1 Associations and the 2x2 Table
Total
a b
dc
2 x 2 Table
Suicide Higher in Areas with Guns
Areas with Guns
No SuicideSuicide
Areas without Guns
DrugEpi 3-1 Associations and the 2x2 Table
Total
a b
dc
People who are exposed
a b
2 x 2 Table
Suicide Higher in Areas with Guns
Areas with Guns
No SuicideSuicide
Areas without Guns
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
2 x 2 Table
Total
Kids Who Watch R-Rated Movies More Likely to Drink, Smoke
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
2 x 2 Table
R-Rated Movies
TotalDrink & Smoke
Kids Who Watch R-Rated Movies More Likely to Drink, Smoke
Do Not Drink & Smoke
No R-Rated
Movies
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
People who are exposed and have the outcome
a
2 x 2 Table
R-Rated Movies
TotalDrink & Smoke
Kids Who Watch R-Rated Movies More Likely to Drink, Smoke
Do Not Drink & Smoke
No R-Rated
Movies
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
2 x 2 Table
Family Meals Are Good for Mental Health
Total
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
2 x 2 Table
Family Meals Are Good for Mental Health
Family Meals
Total
Good Mental Health
Poor Mental
Health
No Family
Meals
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
People who are not exposed and do not have the outcome
d
2 x 2 Table
Family Meals Are Good for Mental Health
Family Meals
Total
Good Mental Health
Poor Mental
Health
No Family
Meals
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
2 x 2 Table
Study Links Iron Deficiency to Math Scores
Total
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
2 x 2 Table
Study Links Iron Deficiency to Math Scores
Iron Deficiency
Poor Math
Scores
No Iron
Deficiency
Good Math
Scores Total
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
People who do not have the outcome and are not exposed
d
2 x 2 Table
Study Links Iron Deficiency to Math Scores
Iron Deficiency
Poor Math
Scores
No Iron
Deficiency
Good Math
Scores Total
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
2 x 2 Table
Pollution Linked with Birth Defects in US Study
Total
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
2 x 2 Table
Pollution Linked with Birth Defects in US Study
Pollution
Birth Defects
No Pollution
No Birth
Defects Total
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
People who are not exposed
dc
2 x 2 Table
Pollution Linked with Birth Defects in US Study
Pollution
Birth Defects
No Pollution
No Birth
Defects Total
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
2 x 2 Table
Depressed Teens More Likely to Smoke
Total
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
2 x 2 Table
Depressed Teens More Likely to Smoke
Depression
Smoke
No Depression
Do Not Smoke Total
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
People who do not have the outcome
d
b
2 x 2 Table
Depressed Teens More Likely to Smoke
Depression
Smoke
No Depression
Do Not Smoke Total
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
2 x 2 Table
Smoking Linked to Youth Eating Disorders
Total
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
2 x 2 Table
Smoking Linked to Youth Eating Disorders
Smoke
Eating Disorders
Do Not Smoke
No Eating
Disorders Total
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
People who are exposed and do not have the outcome
b
2 x 2 Table
Smoking Linked to Youth Eating Disorders
Smoke
Eating Disorders
Do Not Smoke
No Eating
Disorders Total
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
2 x 2 Table
Total
Study Links Spanking to Aggression
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
2 x 2 Table
Study Links Spanking to Aggression
Spanking
Aggression
No Spanking
TotalNo
Aggression
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
People who have the outcome
a
c
2 x 2 Table
Study Links Spanking to Aggression
Spanking
Aggression
No Spanking
TotalNo
Aggression
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
2 x 2 Table
Total
Snacks Key to Kids’ TV-Linked Obesity
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
2 x 2 Table
Snacks Key to Kids’ TV-Linked Obesity
Snacks
Obesity
No Snacks
No Obesity Total
DrugEpi 3-1 Associations and the 2x2 Table
a b
dc
2 x 2 Table
Snacks Key to Kids’ TV-Linked Obesity – China Study
Snacks
Obesity
No Snacks
No Obesity Total
People who are not exposed and have the outcome
c
DrugEpi 3-1 Associations and the 2x2 Table
Big Ideas in this Lesson (3-1)
• An association is when two things “turn up together”
• Epidemiologists study associations • Descriptive epidemiology generates hypotheses about
associations and analytical epidemiology tests hypotheses about associations
• The 2x2 table is a tool used to express the numbers of people with and without the exposure and with and without the outcome. In this way it includes controls.
This project is supported by a Science Education Drug Abuse Partnership Award, Grant Number 1R24DA016357-01, from the National Institute on Drug Abuse,
National Institutes of Health.
Re-Cap
DrugEpi 3-1 Associations and the 2x2 Table
6.
Where are we?Next Lesson
Hypothesis: Buprenorphine will stop heroin addicts from using heroin.
In the next Lesson, 3-2, students will learn about how an experimental study can test hypotheses between an exposure and a beneficial health-related effect
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