Chapter 8: Experimental Study Designs

Question 1

Experimental Study Design?

Answer 1

-Manipulation of study factor: exposure
timing 
intensity
duration
-randomization of study subjects: intervention
receipt 
no receipt

Question 2

What is a quasi-experimental design?

Answer 2

a study in which the investigator is unable to randomly allocate subjects to the conditions (interventions or control) of the study

Question 3

Intervention study?

Answer 3

an investigation involving intentional change in some aspect of the status of the subjects. Employed to test the efficacy of of a preventative or therapeutic measure

Question 4

controlled experimental studies?

Answer 4

involve randomization of subjects to exposures under the control of the investigator

Question 5

quasi-experimental studies?

Answer 5

involve external control of exposure w/o randomization

Question 6

Intervention designs include?

Answer 6

• clinical trials (focused on the person)

- community trials/intervention (focused on the community)

Question 7

A clinical trial?

Answer 7

a research activity that involves the administration of a test regimen to humans to evaluate its efficacy or its effectiveness and safety. The term is broadly polysemic [capable of having several possible meanings]: meanings include from the first test of a drug in humans [refer to foregoing examples] without any control treatment to a
rigorously designed RANDOMIZED CONTROLLED TRIAL
-Ex: pg. 854

Question 8

What’s a polyphylactic trial?

Answer 8

designed to evaluate the effectiveness of a substance or program

• Ex: a vaccine against measles or polio
• Ex: vitamin supplementation or patient education

Question 9

What’s a therapeutic trial?

Answer 9

the study of a new surgical procedure or curative drugs to evaluate how well they bring about an improvement to the patient’s health

Question 10

What are clinical end points?

Answer 10

outcomes, or results of clinical trials

Question 11

Effectiveness?

Answer 11

the extent to which a specific intervention, procedure, regimen, or service produces a beneficial result under ideal conditions; the benefit to the person

Question 12

Efficiency?

Answer 12

the effects or end results achieved in relation to the effort expended in terms of money, resources, and time

Question 13

What is a placebo?

Answer 13

a nonactive medication that resembles the drug being tested in the trial
-the placebo effect is when a person may believe that a pill or treatment will heal them though that treatment (placebo) does nothing

Question 14

What is a single blind design?

Answer 14

the subject is unaware of group assignment, although informed consent is obtained before assignment. They don’t know if they’re in the “control (placebo) group” or “treatment group”

Question 15

What is a double blind design?

Answer 15

used to reduce the likelihood of biased assessment. neither the subject or the experimenter is aware of the group assignment (treatment or control)

Question 16

What happens in Phase I of clinical trial?

Answer 16

Small study to evaluate the safety of a treatment for humans

Question 17

What happens in Phase II of clinical trial?

Answer 17

Study to assess the efficacy of and safety of treatment

Question 18

What happens in Phase III of clinical trial?

Answer 18

Large randomized study to evaluate effectiveness, monitor side effects

Question 19

What happens in Phase IV of clinical trial?

Answer 19

Post-market study to monitor risks, benefits, and optimal use

Question 20

What is fixed randomization?

Answer 20

once subjects have been selected, pass the eligibility determination, and agree to participate, they have an equal probability of of being assigned to the intervention or control arm

Question 21

What is systematic sampling?

Answer 21

involves choosing every nth member member of a pop. until the desired sample size is reached

Question 22

What is a stratified sample?

Answer 22

requires breaking the study population into subgroups and sampling from each subgroup.

Question 23

What is a treatment crossover?

Answer 23

refers to any change of treatment for a patient in a clinical trial involving a switch in study treatments.
-Figure 8-16 (page 883)

Question 24

A community trial?

Answer 24

an experiment which the unit of allocation to receive a preventive, therapeutic, or social intervention is an entire community or political subdivision. Intervention trials at the level of entire communities
-Figure 8-18 (page 895)

Question 25

What is a cluster randomized trial?

Answer 25

another name for a trial that randomizes units like communities to the conditions of an intervention
-randomizes intact social units like households, hospital wards, classrooms, neighborhoods, primary care practices, etc.

Question 26

What is statistical power?

Answer 26

the ability of the study design to detect the hypothesized outcomes of the study

Question 27

Which of the following is a characteristic of an experimental study?

Answer 27

Exposures assigned to study subjects (usually randomly) as part of the study protocol

Question 28

What is the primary advantage of setting strict inclusion criteria for a randomized clinical trial?

Answer 28

Improve internal validity

Question 29

Subjects serve as their own control in which type of intervention study?

Answer 29

Cross-over

Question 30

Subjects for an exposure-based cohort study would be selected most appropriately from:

Answer 30

Firefighters who respond to emergency calls by putting on heavy protective suit, and thus may develop fatigue during the emergency response