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Lecture 21
Study Guide Handout: Study Questions
19
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Undergraduate 3
12/02/2012

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Term
What are 3 main types of observational study design.
Definition

Cohort

 

Case-Control

 

Cross-sectional

Term
What are Cohort Studies?
Definition
  • They involve comparing disease incidence over time, b/t groups that are found to differ on their exposure or factor of interest
  • Good for studying rare exposures
Term
What are Case-Control Studies?
Definition

exposure vs. non-exposure

 

They compare the frequency of past exposures b/t cases who have the diseas, and controls chosen to reflect the frequency of exposrue in the udnerlying pop at risk.

 

Good for studeying rare diseases/cases

Term
Cross-Sectional Studies
Definition

at a single/specific point in time

 

Studies that ivnolve measuring the prevalence of a disease at a specific point in time

Term
What is an institutional Review Board
Definition
A group in an institution/college that reviews all studies in advance in order to protect the subjects from possible harm.
Term
What are some of the ethical concerns (the Institutional Review Board looks over) when conducting research, especially clinical trials, raises?
Definition

voluntary informed consent of the subjects


confidentiality of the subjects results


anonymity of the subjects results

Term

What is the voluntary informed consent?  

Definition
Whent he subjects of the study are willingly consenting to do the study in full awareness of what the study contends
Term
Who can/can't give voluntary informed consent?
Definition

can: everyone else (?)

 

can't: very young children (assent+parental consent), prison inmates, people w/ mental disorders

Term
What is the difference b/t confidentiality and anonymity?
Definition

Confidentiality is when investigators don't tell outside ppl their subjects results. And anonymity is when the investigators can't tell the difference b/t each subjects individual responses.

 

  • confidentiality: either the investigator doesn't tell outside ppl each subjects response OR the inves. isn't able to identify the responses of indvidual subjects
  • anonymity: Inves. doesn't even know each subjects answer / The project doesn't collect identifying inforfamtaion of indvidual subjects
Term
What is a randomized control trial?
Definition

A specific type of scientific experiment, thee "gold standard" for a clinical trial.

 

Key design feature: Random allocation of subjects to exposure (treatment), no exposure (control), or alternative exposure.

 

(In clinical treatments you randomly assign indivdiuals, in pop. health you randomly assign whole communities)

 

Results from randomized trials can offer a more solid basis for interference of cause and effect.

Term
Whats the purpose of random controlled groups?
Definition
All known and unknown factors that might affect the study outcomes, are appropriationed evenly across the treatment group and the control group.
Term
What is the goal of random controlled groups?
Definition

to eliminate bias 

 

(i.e. this was disproven in our celebrity health exp in class)

Term
What is the assumption of random controlled groups?
Definition
That any effect observed between T (trial group) and C (control group) can be linked to the treatment effect and is not characteristic of the individuals in the group. Assume that RCT prevent bias
Term
What is random assignment?
Definition

The technique of assigning treaments to different treatments or no treatment in randomized control trials.

 

The most important requirement for RA is that each participant has an equl chance to be assigned to a group.

 

 

Term

What is the trade-off between internal validity and external validity with an RCT?  

Definition
Term

What is blinding; double-blinding?

Definition

blinding: is the use of placebos to avoid bias caused by an anticipated effect.

 

double-blinding:  when neither the subject nor the investigator knows the exposure status of the subject

 

clinical trials often use blinding to avoid bias in favor of an anticipated effect.

Term
What is a placebo effect?
Definition
When the placebo of a trial (a purposely ineffectual treatment given to subjects in order to decive them) has a perceived or actualy improvement in the subjects health.
Term
What are some of the additional threats to validity that might even affect an RCT’s results (history, maturation, contagion, testing, statistical regression)?
Definition

history: between time1 and time2, change-prodcuign events (external to study) may be occuring in addition to the Treatment Group


maturation: Processes within the respondents operating as a function of passage of time that accoung fro some of T


contagion: Respondents in control group experience T


testing: Effects of taking the same test multiple times, might change results/Effect of taking a test upon the scores of a second testing.


statistical regression: extreme outliers at time1 can really only change in one direction at time 2 (regardless of effect of T)

Term

In a case control study, when you cannot randomly assign your study subjects to an exposure, how might matching reduce confounding? 

Definition
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