Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

epidemiology > ch 7 - experimental study > Flashcards

ch 7 - experimental study Flashcards

1
Q

what is an experimental study? defining feature of study? other names?

A
  • investigator assigns study participants to two groups; one group receives the exposure of interest, and the other does not. Then, the investigator follows the groups over time for the incidence of disease.
  • investigator assigns study subjects
  • intervention studies, clinical trials, and randmized clinical trials
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the format of an experimental study?

A
  • Enrollment based on eligibility criteria
  • Investigator assigns exposure to the members of the source population
  • Time
  • Compare the incidence of the outcome in treatment and comparison groups
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is an experimental study trying to replicate?

A
  • lab experiment that is controlled for everything except for the test chemical
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what does the research question involve in experimental studies? key difference from observational?

A
  • involves prevention or treatment. Feasible and ethical, small effect expected
  • investigator intervenes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the research question in observational studies? key feature?

A
  • nvolves prevention treatment or causal factor, an experimental study is not feasible or ethical. Moderate or large effect expected.
  • he investigator watches
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

equipoise? when is a study appropriate?

A
  • a state in which the investigator truly do not know whether one treatment is better than the other but truly believes that withholding treatment from study participants will not harm them
  • An experimental study is only appropriate and ethical when equipoise is present
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Prevention trial

A
  • agent is given to healthy or high-risk individuals to prevent disease occurrence.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Therapeutic (clinical) trial-

A

agent given to diseased individuals to treat or cure disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Individual trial?

A
  • treatment allocated to individuals
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Community trial

A

treatment allocated to the entire community

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

parallel trial

A

individuals in each group simultaneously will receive one study treatment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Crossover trial

A

two or more study treatments are administered one after another to each group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Factorial trial

A
  • two or more treatments are combined in a factorial trial
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Simple trial

A

Each group receives a treatment consisting of one component

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are the considerations need for a study pop?

A
  • People with a high likelihood of compliance with treatment likely to be followed for the total study period
  • We may need to exclude certain people, such as those with conditions for which the drug under study is contraindicated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Generalizability

A
  • he extent to which the results from a study can be generalized (or extended) to people who did not participate in the study
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

why is the selection of the study population important? what happens if there are too many inclusions or exclusions?

A
  • it directly impacts whom the results generalize once the study is over
  • study loses generalizability.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is a reference population?

A
  • : a group whose results are applicable/generalizable
  • examples: All humans
    All men/women
    Urban children at risk of lead poisoning
19
Q

what is the purpose of sample size

A
  • to determine a true difference between treatment and comparison groups, enrollment of an adequate number of study subjects is necessary
20
Q

what is statistical power in terms of sample size?

A

= ability to demonstrate an association if one exists. Power ranges from 0-100%, good power is >80%

21
Q

what sizes do trials require? what is needed when the sample difference is small?

A
  • Most trials require a large number of participants
  • smaller the anticipated difference between the treatment and comparison groups, the larger the necessary sample size
22
Q

when are null results common?

A
  • Null results are more common in sample sizes that are too small, and power is too low to detect differences
23
Q

How do investigators decide how many subjects to include in a trial?

A
  • Annotated differences between the treatment and comparison groups
  • The background rate of the outcome
  • The proablity of making statistical errors known as alpha and beta errors
24
Q

what does the Institutional review board (IRB) do? what do investigators need to do?

A
  • must approve study protocol before initiating these procedures
  • submits detailed protocol including consent, recruitment, and exposure assignment.
25
Q

what msut all eligible inidvuals do to be enrolled in a trial?

A

give consent that includes a clear explanation of research goals and methods, risks and benefits of participating, assurance of confidentiality, right to withdraw.

26
Q

randomization? what can it minimize?

A

Each study participant has the same probability of receiving treatment and is meant to prevent biased group assignment
- inaccurate results caused by confounding

27
Q

Confounders? how are risk factors distribiuted?

A
  • a factor that distorts the true association between exposure and outcome
  • unequally across groups
28
Q

what is the ultimate goal of randomization balancing confounders?

A
  • treatment is the only difference between study groups
29
Q

what does randomization mean by creating two groups that are the same?

A
  • At baseline, treatment, and comparison group characteristics are balanced
  • With randomization, this occurs for both known and unknown confounders
30
Q

when does randomization work?

A
  • The study is large enough
  • The investigator does not influence the treatment assignment
31
Q

what is masking?

A

method of ensuring that the participants and or study investigators do not know whether a study participant has been assigned to the treatment or comparison group - not always possible

32
Q

what is single, double and triple blind?

A

Single-blind- study participant does not know
Double-blind - study participant does not know, and the study investigator administering the treatment.
Triple-blind - study participant does not know and study investigator administering the treatment and investigator analyzing effects

33
Q

Why use a placebo?

A

Makes exposed and unexposed groups’ experiences as comparable as possible (this goal harkens back to lab experiments)
(method of blinindg)

34
Q

when can placebos not be used?

A

Interventions such as surgery
It is not always ethical; often use current standards of care instead of a placebo

35
Q

power of suggestion

A

Placebo effect participants assigned to the placebo group improve because they are told that they will, which stems from the

36
Q

Hawthorne effect -

A

participants in an experimental study either consciously or unconsciously change their behavior because they are being studied

37
Q

compliance? goal?

A
  • following the study protocol exactly as required throughout the course of the trail
  • have groups be as alike as possible on other important characteristics (randomization)
  • have groups be as different as possible on exposure
38
Q

what effect does non-compliance have?

A
  • tends to make treatment and comparison groups more alike
  • reduces the ability to detect a difference between groups (when groups become to similar)
39
Q

what does noncompliance do?

A

nce tends to bias toward the null

40
Q

what are the measures of frequency?

A

Set up a 2x2 table
CI or IR in treatments and comparison
RD or RR comparing treatment and comparison groups

41
Q

Intention to treat analysis groups? good and bad?

A
  • (treatment vs comparison group)
  • Maintains randomization and - good: Gives a real-life picture
  • bad: But maybe biased towards null due to non-compliance
42
Q

Efficacy analysis
group? good and bad?

A
  • Compliers from the treatment group vs compliers from the non-compliers group
  • Positives: evaluate the effect of treatment in people treated (compliant)
  • Negatives: loss of benefits of randomization and does not give a real-life picture
43
Q

why cant Experimental studies always be used?

A

Practical issues: cost, compliance, follow-up
Ethical issues: equipoise
Many methods we implement in other epidemiology study designs are designed to mimic RCTse

epidemiology (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions