Lesson 2-6: Cross-Sectional Study – In Class Teacher Note: Module 2 Overview Content Area:...
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Transcript of Lesson 2-6: Cross-Sectional Study – In Class Teacher Note: Module 2 Overview Content Area:...
Lesson 2-6: Cross-Sectional Study – In Class
Teacher Note: Module 2 Overview
Content Area: Hypothesis-Testing: Cross-Sectional Study
Essential Questions: How can I select groups of people and collect data/evidence from them that will test my hypothesis? If my causal hypothesis is correct, how would the exposure and outcome be distributed in these groups? Enduring Understanding: Causal hypotheses can be tested by conducting investigations of the exposures and outcomes of selected groups of people as they go about their lives. Information from these observational studies can be used to determine if an exposure and an outcome are associated. Because observational studies are complicated by factors not controlled by the observer, when an association is found, other explanations in addition to causality also must be considered.
Core Concepts:• Testing hypotheses• Association• Exposure/outcome• Control group• 2x2 table• Observational studies• Study design/study plan• Study samples• Prevalence rate• Prevalence ratio• Statement of effect
Lessons:
2-1 Looking for Associations
2-2 Cross-sectional Studies
2-3 Developing Hypothesis and Study Questions
2-4 Respect – Part II
2-5 Planning Study Conduct
2-6 Cross-Sectional Study - In Class
2-7 Cross-Sectional Study – In School
1Revised Sept 16, 2011
Lesson 2-6: Cross-Sectional Study – In Class
Teacher Note: Enduring Epidemiological Understandings for the Epidemiology and the Energy Balance Equation Curriculum
1. Health and disease are not distributed haphazardly in a
population. There are patterns to their occurrence that can be identified through surveillance. Analysis of the patterns of health and disease distribution can provide clues for formulating hypotheses about their possible causes.
2. Causal hypotheses can be tested by conducting investigations of the exposures and outcomes of selected groups of people as they go about their lives. Information from these observational studies can be used to determine if an exposure and an outcome are associated. Because observational studies are complicated by factors not controlled by the observer, other explanations also must be considered.
2
Lesson 2-6: Cross-Sectional Study – In Class
Teacher Note: Authentic Assessment for Module 2 of the Epidemiology and the Energy Balance Equation Curriculum
3
Students will conduct, analyze, and interpret observational, cross-sectional studies among students in their class and then among students outside their class. Working in teams, students will have the opportunity to demonstrate their abilities to select a reasonable hypothesis of interest to them, design study questions about exposure and outcome, obtain informed consent, collect and manage data, calculate and compare prevalence rates, make accurate statements about whether their data support that hypothesis, and consider alternate explanations for what they observed. Reporting of results will be required, such as a written report, an item for the school newspaper, or an oral presentation or poster for students, teachers, and/or parents. Specific performance criteria will be used to help ensure that the experiences allow a genuine, realistic, and fair assessment of students’ comprehension of the Module 2 Enduring Epidemiological Understanding.
Lesson 2-6: Cross-Sectional Study – In Class 4
Teacher Note: Photos of Worksheets for Lesson 2-6
2-5a2-3a 2-3d
2-6a
Lesson 2-6: Cross-Sectional Study – In Class
Start of Lesson 2-6
(estimate 4 class periods)
5
Lesson 2-6: Cross-Sectional Study – In Class 6
Big Idea in Lesson 2-5
• Before the study begins, all materials should be ready and all tasks listed and assigned
Review
Lesson 2-6: Cross-Sectional Study – In Class
Lesson 2-6: Conducting Cross-Sectional Studies in Class
Study Day
7
Lesson 2-6: Cross-Sectional Study – In Class
2-3Study Hypothesis - Statement of a hypothesized association between an exposure and an outcome
2-3Study Variables - Developing questions about exposure and outcome , and additional questions about participants
2-3Questionnaire - Preparing a one-page sheet that study participants will fill out (typed and copies made)
2-4Draft Informed Consent Script - Preparing a script to be read to possible study participants (typed and copies made)
2-5 Plans for Study Conduct – Having assignments for study day
8
Notebook
Study
2-3a - All study planning components should be checked.
Lesson 2-6: Cross-Sectional Study – In Class 9
All
assignments
should be
made and
all plans
be in
order.
2-5a
Assignments for Day of Study Notebook
Study
Lesson 2-6: Cross-Sectional Study – In Class
2-5a, Item 2 - Final Preparation for Each Study Team
10
Supplies
Practice
Informed Consent ScriptI am about to give you a Question / Answer
Form on which a question is written. Do not
write your name on the form. I am going to
ask you to answer the question by circling
your answer with a No. 2 pencil and then
immediately folding the form in half so that
no one else can see your answer. You do
not need to answer the question. If you do
not wish to participate, simply fold the form
in half. Your participation is voluntary,
anonymous, and confidential. Let me repeat
– You are not required to participate and
nothing will happen to you if you do not. I
will pass several large envelops around the
class into which you can place your folded
form regardless of whether or not you
answered the question.
Enough copies of questionnaire for participants
Lesson 2-6: Cross-Sectional Study – In Class 11
Next Class
Conducting In-Class Surveys
Lesson 2-6: Cross-Sectional Study – In Class
2-5a, Item 3 - Conduct Cross-Sectional Studies In-Class One at a Time
One at a time, each study team will do the following:• Introduce team
• Read informed consent statement and remind class of their right to not participate.
• Review questionnaire with the entire class
+ Read over all the questions
+ Remind them to NOT write their name on the paper
• Instruct participants to voluntarily and anonymously fill out the questionnaire.
• When they are finished, instruct students to fold their paper in half and to put the paper into the large envelope that will be passed around (participants and non-participants should do this)
• Thank participants.
CDC
12
Lesson 2-6: Cross-Sectional Study – In Class 13
Conducting Each Study
Have the first study
team pass out the
questionnaire and
proceed with the
study steps outlined
on the previous slide
Notebook
Study
Lesson 2-6: Cross-Sectional Study – In Class
Conduct Cross-Sectional Study In-Class One at a Time
CDC
14
One at a time, each study team will do the following:• Introduce team
• Read informed consent statement and remind class of their right to not participate.
• Review questionnaire with the entire class
+ Read over all the questions
+ Remind them to NOT write their name on the paper
• Instruct participants to voluntarily and anonymously fill out the questionnaire.
• When they are finished, instruct students to fold their paper in half and to put the paper into the large envelope that will be passed around (participants and non-participants should do this)
• Thank participants.
Lesson 2-6: Cross-Sectional Study – In Class 15
Honor RollTotal
12070 50
No Honor Roll
120No Healthy Breakfast 7050
Healthy Breakfast
Prevalence Rates
Total Study Population
Lesson 2-6: Cross-Sectional Study – In Class 16
Honor RollTotal
12070 50
No Honor Roll
70
120or 58%
120No Healthy Breakfast 7050
Healthy Breakfast
Prevalence Rates
Total Study Population
Lesson 2-6: Cross-Sectional Study – In Class 17
Honor RollTotal
12070 50
No Honor Roll
70
120or 58%
120No Healthy Breakfast 7050 or
Healthy Breakfast
Prevalence Rates
50
12042%
Total Study Population
Lesson 2-6: Cross-Sectional Study – In Class 18
Honor RollTotal
12070 50
No Honor Roll
70
120or 58%
120No Healthy Breakfast 7050
Prevalence Ratio
or
Healthy Breakfast
Prevalence Rates
50
12042%
1.4
Total Study Population
Students who eat a healthy breakfast are 1.4 times as likely to make the honor role compared to students who do not eat a healthy breakfast.
Lesson 2-6: Cross-Sectional Study – In Class 19
Next Class
Data Analysis
Lesson 2-6: Cross-Sectional Study – In Class
Data Management and Calculations for the In-Class Cross-Sectional Study
20
2-6a Notebook
Study
Lesson 2-6: Cross-Sectional Study – In Class21
Next Class
Report Out
Lesson 2-6: Cross-Sectional Study – In Class22
What are the limitations of these studies?
Lesson 2-6: Cross-Sectional Study – In Class23
Mistakes
Lesson 2-6: Cross-Sectional Study – In Class24
Guilt by Association
Lesson 2-6: Cross-Sectional Study – In Class25
Which happened first?
Lesson 2-6: Cross-Sectional Study – In Class
2-6a Basis for Report Out and Discussion
26
Notebook
Study
Lesson 2-6: Cross-Sectional Study – In Class
1. 2x2 tables and calculations
2. Accurate statements about results
3. Do the results support the hypothesis?
4. What limitations exist?
Report Out and Discussion of Results In Class
27
Lesson 2-6: Cross-Sectional Study – In Class 28
Assessment of Simulated Research Experience
Study PlanningTeamwork
Report Out
Respect for Participants
Study Conduct
Understanding of Study Strengths and Limitations
Data Analysis
Interpretation
of Study
Data Management
Study Communications
Lesson 2-6: Cross-Sectional Study – In Class
Preview of Rubric for Evaluating In-School Studies
29
Criteria Got It Getting It Will Get It SoonParticipation All study team
members participateMost study team members participate
Some study team members participate
Use of Epidemiology Terminology such as Prevalence, Prevalence Ratio, and others
All are appropriate and accurate
Most are appropriate and accurate
Some are appropriate and accurate
Understanding of Importance of Informed Consent
Full understanding of importance
Some understanding of importance
Limited understanding of importance
Thoughtful discussion of challenges in data collection and management
At least 2 challenges well discussed
One challenge well discussed
Little discussion of challenges
Accurate calculation of prevalence and prevalence ratio
All prevalence rates and ratios correctly calculated
Some correctly calculated
Mostly or completely incorrectly calculated
Thoughtful discussion of whether the data support or do not support the hypothesis
A thorough and reasonable discussion of whether the data support the hypothesis
Some reasonable thoughts about whether the data support the hypothesis
Little thoughtful discussion of whether the data support the hypothesis
Understanding of limitations of their study
Identified at least 2 reasonable and logical limitations
Identified 1 reasonable and logical limitation
Did not identify any reasonable or logical limitations
Lesson 2-6: Cross-Sectional Study – In Class 30
Big Ideas in Lesson 2-6
• The in-class studies are final practice for conducting the in-school studies
• This is simulated research, not actual research, because the results are not generalizable
• Steps and materials should all be ready prior to starting
• In all aspects of the study, every effort should be made to protect the privacy of participants and their information
• The study allows us to test a hypothesis: it yields counts, that can be turned into prevalence rates, that can be compared as a prevalence ratio, that provides information about an association versus no association
Re-Cap
Lesson 2-6: Cross-Sectional Study – In Class 31
Optional additional session
As appropriate for your class, and as time allows, use these few additional slides from
the CHIS study article to stimulate discussion about limitations of their studies
and cross-sectional studies in general
Lesson 2-6: Cross-Sectional Study – In Class 32
As appropriate for your class, and as time allows, use these few additional slides from
the CHIS study article to stimulate discussion about limitations of their studies
and cross-sectional studies in general
Lesson 2-6: Cross-Sectional Study – In Class
More Information about CHIS Study
Theresa A. Hastert, Susan H. Babey. School lunch source and adolescent dietary behavior. Prevention of Chronic Diseases 2009; Vol 6 (4)
http://www.cdc.gov/pcd/issues/2009/oct/08_0182.htm
33
Lesson 2-6: Cross-Sectional Study – In Class 34
Typical Study Abstract
Introduction
Methods
Results
Conclusion
Lesson 2-6: Cross-Sectional Study – In Class 35
Abstract
IntroductionAs rates of childhood obesity rise, the nutritional content of lunches eaten at school is more heavily scrutinized. We examined the association between dietary behaviors and the number of days that adolescents bring lunch to school.
MethodsWe analyzed cross-sectional data for 2,774 adolescents who responded to the 2005 California Health Interview Survey and reported dietary behaviors for a weekday.
Lesson 2-6: Cross-Sectional Study – In Class 36
Abstract (continued)ResultsIn bivariate analyses, adolescents who typically brought their lunch from home 5 days per week ate fast food on fewer occasions; consumed fewer servings of soda, fried potatoes, and high-sugar foods; and ate more fruit and vegetables compared with adolescents who never brought their lunch to school. In linear regressions controlling for demographics, body mass index, desire to change weight, parent education, and adult presence after school, students who typically brought their lunch to school 5 days per week ate fast food 0.35 fewer times and consumed 0.35 fewer servings of soda, 0.10 fewer servings of fried potatoes, 0.25 fewer servings of high-sugar foods, and 0.95 more servings of fruit and vegetables per day compared with students who never brought their lunch to school.
Lesson 2-6: Cross-Sectional Study – In Class 37
ConclusionThese findings suggest that adolescents who bring lunch to school from home have more positive dietary behaviors than do adolescents who get their lunches from other sources. Improving the nutritional quality of foods offered from other sources, such as the National School Lunch Program and competitive foods, could help improve adolescent dietary behaviors.
Abstract (continued)
Lesson 2-6: Cross-Sectional Study – In Class 38
“ This study has several limitations.”
“The dietary intake data are self-reported, making them subject to errors.”
“A single question was used to address each dietary behavior, and questions ask about diet on the previous day, which might not be representative of the respondents’ overall diet patterns.”
“Additionally, we did not assess or control for the social desirability of bringing lunch.”