1. Quasi-Experiment
1.1. Explanation: Community Trials
1.1.1. Advantage: True Experiments
1.1.1.1. Strength: Better Control of Variables
1.1.1.1.1. Example: Comparing the grades of college students at different schools that receive tutoring from a new program and the ones that do not
1.1.1.2. Weakness: Chance of Inaccuracy
1.1.2. Disadvantage: Difficult to Access
2. Prospective Cohort
2.1. Explanation: Longer Cohort Study
2.1.1. Advantage: Calculation of incidence
2.1.1.1. Disadvantage: Follow up bias
2.1.1.1.1. Strengths: Data collection from various sources
2.1.1.2. Disadvantage: Not useful for rare situations
2.1.1.2.1. Weakness: Follow a Large Population for an Extended Time
2.1.1.2.2. Weakness: Time and Cost
2.1.2. Advantage: Prevent Selection Bias
3. Retrospective Cohort
3.1. Explanation: Observes historic data to determine the risk of disease between exposed and nonexposed.
3.1.1. Advantage: Less Expensive
3.1.1.1. Strength: Data for a large number of patients.
3.1.1.1.1. Example: Interviewing HIV-Positive individuals.
3.1.1.2. Weakness: Bad for rare diseases
3.1.2. Weakness: Losses to Follow Up
3.1.3. Disadvantage: Missing Data from Past
4. Nested Case-Control
4.1. Explanation: Cases and controls collected from the population in a numbered cohort.
4.1.1. Advantage: Cost Reduction
4.1.1.1. Strength: Less Effort
4.1.1.1.1. Example: Historic data showing that women who were not ill, decades later became receptive to cancer due to varying factors.
4.1.1.2. Weakness: Decreased Ability due to Sampling Controls
4.1.2. Advantage: Reduced Bias
4.1.3. Disadvantage: Reduced Accuracy
5. Cross-Sectional
5.1. Explanation: Looking at data from a population at one specific time.
5.1.1. Advantage: Captures a Specific Point in Time.
5.1.1.1. Disadvantage: Does not Determine Cause
5.1.1.1.1. Strengths: Quick
5.1.1.2. Disadvantage: Behavior Overtime Can Not Be Analyzed
5.1.2. Advantage: Not Costly to Perform
5.1.3. Advantage: Multiple Outomes and Exposures Can be Studied.
6. Experimental
6.1. Explanation: Manipulates study factors and randomly assigns subjects to the exposed and nonexposed.
6.1.1. Advantage: Gain Knowlege
6.1.1.1. Disadvantage: Artificial Results
6.1.1.1.1. Strengths: Decide Future
6.1.1.1.2. Weaknesses: Human response is hard to measure.
6.1.1.2. Disadvantage: Subject to Human Error
6.1.1.2.1. Example: Treating Alheizmer's by giving out different dosages to patients for varying results.
6.1.2. Advanatge: Control other Variables
7. Controlled Experiment
7.1. Explanation: Controlled randomization of a subject by the investigator.
7.1.1. Advantage: Cause and Effect
7.1.1.1. Disadvantage: Results Vary
7.1.1.2. Disadvantage: Lack of Reality
7.1.2. Advantage: Single Indepedent Variable
7.1.2.1. Strength: Experimental Variable Isolated
7.1.2.1.1. Example: Receiving randomization of drugs for patients with a disease.
7.1.2.2. Weakness: Unrealistic
8. Ecological
8.1. Explanation: Used to Understand the Relationship between Outcome and Exposure at a Population level.
8.1.1. Advantage: Large number of people included
8.1.1.1. Disadvantage: Exposure is Only Measured Based on Average Population.
8.1.1.1.1. Strength: Exposure data only avaiable at the area level.
8.1.1.1.2. Weakness: Lack of data
8.1.2. Advantage: Large risk modifying factors examined.