• Save
Study designs med_students
Upcoming SlideShare
Loading in...5
×
 

Study designs med_students

on

  • 1,197 views

 

Statistics

Views

Total Views
1,197
Views on SlideShare
1,106
Embed Views
91

Actions

Likes
3
Downloads
0
Comments
0

1 Embed 91

http://www.taibahu.edu.sa 91

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    Study designs med_students Study designs med_students Presentation Transcript

    • Study Designs Dr. Abdulmohsen Alzalabani MBChB, ABCM, MSc(Epi), MHPE Assistant Professor, Community Medicine Chairman, Medical Education Department College of Medicine, Taibah University
    • Research? the process of answering a question by appropriately collected data What is the frequency of a disease in a certain place at a certain time? What caused this disease? Descriptive Hypothesis generation Hypothesis testing the process of developing a list of possible candidates for the “causes”
    • Research question?
      • Is anise effective in prevention of Influenza?
      • هل اليانسون مفيد للوقاية من الانفلونزا؟
    • Define your question
      • Anise:
        • Which Anise?
        • Frequency?
        • Quantity?
      • Treatment:
        • Cure?
        • Relief of symptoms?
        • Reduce duration?
        • Reduce complication?
      • Prevention:
        • Prevention of infection?
        • Prevention of disease?
        • Prevention of complications?
    • Exposure/Intervention and Outcome Intervention Exposure Anise Mobile phones Outcome Outcome Influenza Brain Cancer
    • So, how to answer the question?
    • Mr. Ali is a 50 years old taxi driver in Riyadh. ……………… .. ……………… .. ……………… .. He reported that he drink a cup of Anise everyday. He claimed he never caught flu since he started drinking Anise. Case-report Problems? Anecdotal evidence
    • A group of people aging between 40 and 50 years working as taxi drivers in Riyadh. ……………… .. ……………… .. ……………… .. They reported that they drink a cup of Anise everyday. They claimed they never caught flu since they started drinking Anise. Case-series Problems? Anecdotal evidence
    •  
    • Population Random Sample Drinking Anise Not drinking Anise Cross-sectional Study (Survey) All measured at the same time Influenza No Influenza
    • Cross-sectional studies (surveys)
      • are the simplest type of epidemiological study
      • information is collected from each subject at one point in time
      • information can be on outcomes (e.g. diseases, infections, high blood pressure, low birthweight)
      • information can be on exposures (e.g. smoking, diet, occupation)
      • information can be on both outcomes and exposures (e.g. HIV positivity and injecting-drug use).
    • EXAMPLE : Survey of current headache With headache No headache Total Students in this class
    • EXAMPLE : Survey of current headache With headache No headache Total Students in this class 5 45 50 Prevalence = 5 50 = 0.10 or 10%
    • Population People without Flu Drinking Anise Not drinking Anise Influenza No Influenza Influenza No Influenza Follow-up Cohort Study
    • Population People without disease Exposed Unexposed Disease No disease Disease No disease Follow-up Cohort Study
    • Population Influenza patients People with no Influenza Anise drinker No Anise Anise drinker No Anise Case-Control Study Ask about the past
    • Population Cases (disease) Control (No disease) Exposed Not Exposed Exposed Not Exposed Case-Control Study Ask about the past
    • What was the role of the researcher? Observing only Observational Studies Case-control Cohort Cross-sectional Case-series Cross-sectional Case-report Descriptive Studies Analytic Studies Prevalence Distribution Description Testing Association Difference
    •  
    • Experimental studies Normal people Give “Anise” Influenza No Influenza Before-after Problems? Follow-up
    • Experimental studies Normal people Give “Anise” Influenza No Influenza Controlled Trial Problems? Normal people Give “Nothing” Influenza No Influenza Follow-up
    • Experimental studies Normal people Give “Anise” Influenza No Influenza Randomized Controlled Trial (RCT) Problems? Normal people Give “Nothing” Influenza No Influenza Normal people randomize Follow-up
    • How do you go about designing a study?
      • Decide which is the outcome and which is the (primary) exposure
      • Is the outcome rare?
      • Is the exposure rare?
      • Any existing, useful, databases?
    • General concerns with all types of studies
      • Clear definitions of exposure and outcome
      • Use valid/reliable methods
      • Non-response can introduce bias
      • The primary concern in the design of any study must be validity
      • Large enough sample size
      • Do not over-interpret associations