8: Experimental Study Design Flashcards

1
Q

Validity

A

the extent to which a test measures what it claims to measure. Experimental study has highest validity

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2
Q

Experimental Studies

A

most rigorous design. greatest control over research setting. manipulation and randomization. typically as intervention study. ethical situation.

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3
Q

Quasi-Experimental/Community Trial

A

immediately below controlled experiments in rigor. unable to randomize due to ethics. may be contamination across conditions of study from people moving

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4
Q

Intervention Studies

A

used to test efficacy of preventive or therapeutic measures. multicenter trials.

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5
Q

Intervention Study Categories

A

Controlled Clinical Trials vs. Community Interventions

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6
Q

Multicenter Trials

A

results from several researchers are pooled, giving diverse population

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7
Q

Why did early history not follow method of intervention study? (Jenner’s smallpox vaccine)

A

no control group. only a few participants

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8
Q

Ambroise Pare

A

applied experimental treatment for battlefield wounds. CLINICAL TRIALS

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9
Q

East India Shipping Company, James Lind

A

used concurrently treated control group method. provided sailors different types of diet. found lemon juice protected against scurvy. CLINICAL TRIALS

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10
Q

Captain Cook

A

insisted on obtaining fresh water and vegetables at every opportunity. no deaths from scurvy in initial voyages. CLINICAL TRIALS

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11
Q

Clinical Trials

A

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)

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12
Q

Prophylactic Trial

A

evaluates effectiveness of a substance that is used to prevent disease. can involve a prevention program.

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13
Q

Therapeutic Trial

A

involves the study of curative drugs or a new surgical procedure to improve the patient’s health.

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14
Q

Clinical End Point

A

outcome of clinical trials. compare rates of disease, death, recovery, or other outcome. must be measured in a comparable manner in both groups

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15
Q

Blinding (Masking)

A

to maintain integrity of a study and reduce potential for bias. Single-blind vs. Double-blind

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16
Q

Single-Blind Design

A

subject unaware of group assignment

17
Q

Double-Blind Design

A

neither subject nor experimenter is aware of group assignmnet

18
Q

Phase 1 Clinical Trial

A

test new vaccine in <100 adult volunteers. IS IT SAFE??

19
Q

Phase 2 Clinical Trials

A

Expands testing to group of 100-200. immunogenicity and reactogenicity evaluation

20
Q

Phase 3 Clinical Trials

A

assess efficacy of vaccine in TARGET POPULATION. main test.

21
Q

Phase 4 Clinical Trials

A

post-marketing research to gather more information about risks and benefits of a drug

22
Q

Randomization

A

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

23
Q

Stratify

A

categorizing into groups. stratify then randomize

24
Q

Crossover Designs

A

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

25
Q

Institutional Review Boards (IRB)

A

ethical review of studies

26
Q

Tuskegee Syphilis Experiment

A

prevented treatment with penicillin. didn’t tell participants they had syphilis. allowed for spouses to contract disease and children born with congenital syphilis.

27
Q

CONSORT Statement

A

Consolidated Standards of Reporting Trials. protocol that guides reporting of randomized trials by providing 22-item checklist and flowchart. method to optimize quality of reporting

28
Q

Clinical Trials Strengths

A

greatest control over amount of exposure, timing and frequency of exposure, and period of observation. ability to randomize reduces likelihood groups differ significantly.

29
Q

Clinical Trials Limitations

A

Artificial setting. limited scope of potential impact. adherence to protocol difficult to enforce. ethical dilemmas

30
Q

Thalidomide

A

suppose to treat morning sickness. massive side effects appeared after making available to larger population. caused major birth defects

31
Q

Community Trials

A

determine potential benefit of new policies and programs. often educational campaigns . start by determining eligible communities and willingness to participate. use variety of measures. make use quasi-experimental design (manipulation but no randomization)

32
Q

Community Trials Intervention

A

any program or other planned effort designed to produce changes in a target population.

33
Q

Community Trials Advantages

A

represent only way to estimate directly the impact of change in behavior or modifiable exposure on the incidence of disease

34
Q

Community Trials Disadvantages

A
  • inferior to clinical trials with respect to ability to control entrance into study, delivery of intervention, and monitoring of outcomes
  • fewer study units capable of randomization, affecting comparability
  • affected by population dynamics, secular trends, and nonintervention influences
35
Q

Four Stages of Evaluation of an intervention

A
  1. Formative: plans work as conceived?
  2. Process: serving target group as planned?
  3. Impact: changes in target group?
  4. Outcome: accomplish ultimate goal?
36
Q

Quasi-Experimental Designs

A
  • Posttest only
  • Pretest/Posttest
  • Pretest/Postest/Control
37
Q

Solomon Four-Group Assignment (quasi-experimental design)

A

uses four equivalent groups, two intervention and two control. two observed before and after intervention, two observed only after intervention. used to overcome Hawthorne Effect

38
Q

Hawthorne Effect

A

improvement or modify behavior because they are a part of the study. “tendency to perform”