Experimental studies- quiz

Question 1

What happens under intervention studies?

Answer 1

1) The investigators influence exposure of study subjects
2) manipulation and randomization
3) two types of experimental trials fall here :

controlled trials and community trials

Question 2

Why blind patients ?

Answer 2

1) b/c patients try to get well or please physicians.

2) minimize potential bias from a placebo effect

Question 3

what are the disadvantages of an experimental study?

Answer 3

1) limited in application

2) not as helpful as studying etiology(cause)of disease

Question 4

A randomized controlled trial in a clinical setting referred to as?

Answer 4

A clinical trial

Question 5

what are the two types of experimental trials?

Answer 5

1) controlled trials

2) community trials

Question 6

What is the unit of analysis in a randomized controlled trial ?

Answer 6

The individual

Question 7

what are the advantages of randomized controlled clinical trials ?

What are the disadvantages of it ?

Answer 7

Advantages?

1) eliminate conscious bias due to physician/patient selection .
2) averages out unconscious bias due to unknown factor
3) Groups are “alike on avg”

Disadvantage ?

1) Ethical issues
2) interferes w/ doc/ patient relationship

Question 8

what are randomized community trials ?

Answer 8

intervention for purpose of educational/ behavioral changes at population/group level.

Question 9

Selecting outcomes (endpoint)

Answer 9

Primary Endpoint :
whether a new treatment is better at preventing disease-related death than the standard therapy
or

the primary endpoint for most Phase III clinical trials in HIV disease is an AIDS defining event or death.

Selection of “BEST” endpoint is often complicated.

Question 10

What is the purpose of an experimental study ?

Answer 10

Identify clinical & public health approaches to solving public health problems ( how to prevent or treat)

Question 11

What are randomized controlled trials (RTC):

Answer 11

Subjects get randomly assigned to groups which are:

1) study or intervention and control groups
2) receive or not receive treatment.

Question 12

What are the types of randomized controlled trials ?

Answer 12

A prophylactic trial

Therapeutic trial

Clinical trial

Question 13

What is a non-randomized study? (convenience sample)

Answer 13

concurrent comparison group is allocated by a non-random process

Question 14

What is a natural experiment ?

Answer 14

unplanned events can create natural experiment.

Situations that may create appropriate circumstances for a natural experiment include policy changes, weather events, and natural disasters

Question 15

What is a good choice of a comparison group?

Answer 15

• non contaminated by treatment
• idea- possible to blind, usually meaning placebo used.
• status quo vs. new treatment

Question 16

What are the problems that come with blinding ?

Answer 16

• unethical
• sometimes its impossible to do : for example, can’t be done on someone who will have surgery.
• problematic to blind in drug studies, where treatment has side effects.

Question 17

What is a random assignment ?

Answer 17

1) random assignment makes intervention and control groups look as similar as possible
2) chance is only facts that determines group assignment
3) neither patient nor physician know in advance which prevention program or therapy will be assigned
- confounding and sample size in an issue

Question 18

How to measure baseline variables?

Answer 18

Consider measuring outcome variable: know that it can

1) change over time and that
2) disease is/ or not present at baseline

Measure various predictors of outcomes (like smoking habits) to allow for statistical adjustment

Question 19

what’s a Single Blind Study?

Answer 19

placebo controlled study

subjects are blinded but investigator aware of who is receiving active treatment

Question 20

What is the measuring baseline variables?

Answer 20

Demographics(age, race, gender, etc.)
other factors

First table of the report of any of the randomized trials usually compared the level of baseline characteristics in two study groups.

Question 21

What happens in the randomized controlled trial ?

Answer 21

two groups :

A. Group 1: gets placebo
B. Group 2: gets real medicine

*Both are blinded to their
group membership.

*Once time passes, both
groups are then followed-up.

questions will be: will group do better than group 2 ?

Question 22

What are the issues with non-randomized studies?

Answer 22

• non effective at controlling unmeasured confounding variables.
• measured confounding variables, however, may be adjusted through analytic methods.

Question 23

What are group randomizations?

What will group involve?

Answer 23

Groups/ naturally forming clusters are randomly assigned the intervention.

• practices
• schools
• hospitals
• communities

Individuals/patients within clusters are likely to be more similar to each other compared to those in other clusters.

Question 24

What is a Double Blind Study?

Answer 24

Neither subjects nor investigators know who is receiving active treatment

Question 25

What happens in within-Group Design?

Answer 25

Outcome in single group is compared before and after assigned intervention.

Question 26

What happens in Between- Group Design ?

Answer 26

Outcomes compared btw 2 / more groups receiving different levels of treatment.

Question 27

Who are the participants ?

Who will be part of your inclusion/ exclusion criteria?

Answer 27

Inclusion criteria :✔️that the prospective subjects must have if they are to be included in the study
- broad vs specific: extent of generalization to population of interest.

Is the outcome rare?
- then recruit from population at risk.

Exclusion criteria: ❌
Define exclusion criteria that help control error :

ex. advanced cancer may be fatal before end of follow up period.

exclude those who don’t comply:
such as alcoholics, people who are planning to move out and you can’t follow up

Question 28

What happens in a crossover design?

Answer 28

Participants may be switched between treatment groups.

Question 29

What are randomized trial “ community intervention “?

Answer 29

Intervention designed for the purpose of educational and behavioral changes at population or group level

Question 30

what are ethics in research?

Answer 30

1) informed consent
2) delayed control
3) clinica equipoise
4) benefit/risk
5) institutional review board
6) stoppage point
7) sequential design

Question 31

what’s a placebo effect?

Answer 31

Effect on patient outcomes (improved/ worsened) may occur due to expectations by patients that particular intervention will have effect.

Question 32

What are experimental studies for and best for ?

Answer 32

1) controlled experiments performed in scientific research
2) best for relatively mature questions
3) best for finding cause-effect relationships and evaluating efficacy of prevention and therapeutic interventions.

Question 33

What are the three types of blinding?

Answer 33

Single blinding: subjects

Double blinding: investigators

Triple blind: analyses

Question 34

What are the advantages of an experimental study?

Answer 34

1) able to experimentally manipulate exposure

2) able to make strong inferences

Question 35

What is a Tripe Blind Study?

Answer 35

Treatment and research approaches kept a secret from subjects, investigators and analyses are completed in manner that is removed form the investigators.