8: Experimental Study Design Flashcards
(38 cards)
Validity
the extent to which a test measures what it claims to measure. Experimental study has highest validity
Experimental Studies
most rigorous design. greatest control over research setting. manipulation and randomization. typically as intervention study. ethical situation.
Quasi-Experimental/Community Trial
immediately below controlled experiments in rigor. unable to randomize due to ethics. may be contamination across conditions of study from people moving
Intervention Studies
used to test efficacy of preventive or therapeutic measures. multicenter trials.
Intervention Study Categories
Controlled Clinical Trials vs. Community Interventions
Multicenter Trials
results from several researchers are pooled, giving diverse population
Why did early history not follow method of intervention study? (Jenner’s smallpox vaccine)
no control group. only a few participants
Ambroise Pare
applied experimental treatment for battlefield wounds. CLINICAL TRIALS
East India Shipping Company, James Lind
used concurrently treated control group method. provided sailors different types of diet. found lemon juice protected against scurvy. CLINICAL TRIALS
Captain Cook
insisted on obtaining fresh water and vegetables at every opportunity. no deaths from scurvy in initial voyages. CLINICAL TRIALS
Clinical Trials
A planned experiment that assesses the efficacy of a treatment. Outcomes in treated group compared with outcomes in equivalent control group. participants in both groups are enrolled, treated, and followed over same time period. tightly controlled in terms of eligibility, delivery of intervention, and monitoring of outcomes. participation generally restricted to highly selected group of individuals to minimize variability. randomization into intervention or control. more than one experimental intervention can be run in parallel (varying doses)
Prophylactic Trial
evaluates effectiveness of a substance that is used to prevent disease. can involve a prevention program.
Therapeutic Trial
involves the study of curative drugs or a new surgical procedure to improve the patient’s health.
Clinical End Point
outcome of clinical trials. compare rates of disease, death, recovery, or other outcome. must be measured in a comparable manner in both groups
Blinding (Masking)
to maintain integrity of a study and reduce potential for bias. Single-blind vs. Double-blind
Single-Blind Design
subject unaware of group assignment
Double-Blind Design
neither subject nor experimenter is aware of group assignmnet
Phase 1 Clinical Trial
test new vaccine in <100 adult volunteers. IS IT SAFE??
Phase 2 Clinical Trials
Expands testing to group of 100-200. immunogenicity and reactogenicity evaluation
Phase 3 Clinical Trials
assess efficacy of vaccine in TARGET POPULATION. main test.
Phase 4 Clinical Trials
post-marketing research to gather more information about risks and benefits of a drug
Randomization
method of choice for assigning subjects to treatment or control conditions of a clinical trail. non-random assignments may cause mixing of effects of intervention with differences among participants of trial
Stratify
categorizing into groups. stratify then randomize
Crossover Designs
any change of treatment for a patient involving a switch of study treatments. patient may serve as his or her own control. may be on patient’s request, serious side effects, or major health benefits