Study Designs
Understanding Research: An Overview for Health Professionals Week 2: Study Design
Faculty: Abbey Alkon, RN PNP PhD, Professor Teaching Assistant: Jarmin Yeh, PhD Student UCSF School of Nursing
Study Designs
Study Designs o Cohort Studies • Prospective or retrospective • Experimental - Quasi-experimental
o Cross-Sectional Studies o Case-Control studies
Over view of Study Designs Time Frame Present
Crosssectional X
Casecontrol X
Prospective Cohort
Historical Cohort
X X
Present & Future
Past
X
X
Past & Present
X
X
Analysis Descriptive Analytic
X
X
X
X
X
X
X
What’s The Study Design?
http://www.flickr.com/photos/darinrmcclure/9059210910/
How do you know what study design is appr opriate?
Key Questions: o Will there be an intervention? o What types of comparisons are made? o What is the time frame of the study? o How many times will data be collected? o What is the research question?
Will there be an inter vention?
Study Design
Intervention
Cohort
No
Cross-sectional
No
Case-control
No
Experimental
Yes
Alkon @ 2013
W hat is the time frame of the study?
Study Design
Time Frame
Cohort Cross-sectional
Prospective or retrospective One point in time
Case-control
Retrospective
Experimental
Prospective
How many times will data be collected? Study Design
Data collection times
Cohort Cross-sectional
Repeated measures over time One time
Case-control
Usually one time
Experimental
Repeated measures over time
W hat is the research question? Study Design Descriptive Cohort Incidence CrossPrevalence, sectional Associations Case-control None
Experimental Treatment effect
Analytic Association, predictors No causation Identify predictors; Causation
Question •
•
Morbidity reports received by a county health department indicated that a number of young women who developed viral hepatitis after no known exposure to the disease had their ears pierced during the preceding months. To study the association between ear piercing and hepatitis, young women with viral hepatitis and a group of young women of similar age who attended a family planning clinic and did not have viral hepatitis were queried about recent ear piercing. It was found that 7 of the 48 women with hepatitis, but only 1 of the 100 women attending the family planning clinic, had had their ears pierced within the preceding 7 months. What type of study design is this and why?
Case-Control Study 1. Will there be an intervention? No 2. What comparisons are made? Those with and without the diagnosis of hepatitis 3. What is the time frame? Retrospective 4. How many times will data be collected? Once 5. What is the research question? Is there an association between ear piercing and hepatitis in young women?
Question - Answer • • •
• • •
Diagnosis: viral hepatitis in young women Cases: young women with viral hepatitis Controls: young women matched by age with no diagnosis of viral hepatitis Interviews/ Surveys – identify exposure ear piercing during the preceding months Setting: Family planning clinic Results: 7 of the 48 women with hepatitis, but only 1 of the 100 women attending the family planning clinic, had had their ears pierced within the preceding 7 months.
Faculty: Abbey Alkon, RN PNP PhD, Professor Teaching Assistant: Jarmin Yeh, PhD Student UCSF School of Nursing
Study Designs
Study Designs o Cohort Studies • Prospective or retrospective • Experimental - Quasi-experimental
o Cross-Sectional Studies o Case-Control studies
Over view of Study Designs Time Frame Present
Crosssectional X
Casecontrol X
Prospective Cohort
Historical Cohort
X X
Present & Future
Past
X
X
Past & Present
X
X
Analysis Descriptive Analytic
X
X
X
X
X
X
X
What’s The Study Design?
http://www.flickr.com/photos/darinrmcclure/9059210910/
How do you know what study design is appr opriate?
Key Questions: o Will there be an intervention? o What types of comparisons are made? o What is the time frame of the study? o How many times will data be collected? o What is the research question?
Will there be an inter vention?
Study Design
Intervention
Cohort
No
Cross-sectional
No
Case-control
No
Experimental
Yes
Alkon @ 2013
W hat is the time frame of the study?
Study Design
Time Frame
Cohort Cross-sectional
Prospective or retrospective One point in time
Case-control
Retrospective
Experimental
Prospective
How many times will data be collected? Study Design
Data collection times
Cohort Cross-sectional
Repeated measures over time One time
Case-control
Usually one time
Experimental
Repeated measures over time
W hat is the research question? Study Design Descriptive Cohort Incidence CrossPrevalence, sectional Associations Case-control None
Experimental Treatment effect
Analytic Association, predictors No causation Identify predictors; Causation
Question •
•
Morbidity reports received by a county health department indicated that a number of young women who developed viral hepatitis after no known exposure to the disease had their ears pierced during the preceding months. To study the association between ear piercing and hepatitis, young women with viral hepatitis and a group of young women of similar age who attended a family planning clinic and did not have viral hepatitis were queried about recent ear piercing. It was found that 7 of the 48 women with hepatitis, but only 1 of the 100 women attending the family planning clinic, had had their ears pierced within the preceding 7 months. What type of study design is this and why?
Case-Control Study 1. Will there be an intervention? No 2. What comparisons are made? Those with and without the diagnosis of hepatitis 3. What is the time frame? Retrospective 4. How many times will data be collected? Once 5. What is the research question? Is there an association between ear piercing and hepatitis in young women?
Question - Answer • • •
• • •
Diagnosis: viral hepatitis in young women Cases: young women with viral hepatitis Controls: young women matched by age with no diagnosis of viral hepatitis Interviews/ Surveys – identify exposure ear piercing during the preceding months Setting: Family planning clinic Results: 7 of the 48 women with hepatitis, but only 1 of the 100 women attending the family planning clinic, had had their ears pierced within the preceding 7 months.
