Week 7: Design 3 Flashcards
what are observational vs experimental studies?
observational = researchers collect, record and analyze the data on naturally dividing exposure and outcome variables
experimental = researchers assign an exposure to specific study participants/groups to see how this influences the outcome –> manipulation
The defining feature of an experimental feature is that an investigator assigns the _________ to study participants. Experimental studies are sometimes called _________ trials
exposure, clinical
- (experimental/observational) studies are feasible and ethical. (experimental/observational) studies are NOT feasible and ethical.
- (experimental/observational) studies effect (small/large) level populations. (experimental/observational) studies effect (small/large) level populations.
- experimental
observational - experimental, small
observational, large
Compare prevention vs therapeutic (clinical) trials
Prevention = agent is given to healthy or high risk individuals to PREVENT disease occurrence
Therapeutic = agent given to diseased individuals to TREAT or CURE disease
Identify if each situation is a prevention or therapeutic trial
a) Does removing lead contaminated soil prevent lead poisoning in high risk urban children?
b) Does the drug Herceptin lower the risk of recurrence and improve survival among women diagnosed with breast cancer?
c) Does the drug tamoxifen lower the incidence of breast cancer in high-risk women?
a) prevention trial
b) therapeutic trial
c) prevention trial
- Compare individual vs community trials
- identify if each situation is an individual or community trial:
a) Study impact of drinking water fluoridation on frequency of dental caries in one community (e.g., Newburgh, NY) versus no fluoridation in a similar community (Kingston, NY)
b) Study effectiveness of treatment with two drugs versus three drugs among adults infected with HIV
- individual trial = treatment allocated to INDIVIDUALS, community trials = treatment allocated to entire COMMUNITY
- a) community trial
b) individual trial
- choice of population in a study depends on the _______ of the trial
- an increase in inclusion/exclusion criteria in a study (increases/decreases) generalizability
- the investigator must submit a detailed _______ including consent, recruitment, exposure assignment.
- all eligible individuals must give _________ BEFORE enrolling in a trial
- purpose
- decreases
- protocol
- consent
- what is randomization in an experimental study? Why is randomization important?
- T/F: Chance differences between groups due to sampling error are more likely to occur when the study sample is larger
- randomization in experimental studies creates similarity between groups for potential _________ variables
- means that each study participant has the same probability of receiving the treatment- assignment to experimental and control is random. it prevents biased assignment of the treatment
- F. when sample size is smaller
- confounding
- What is blinding (masking)?
- explain single, double and triple blinds
- a method of ensuring that participants/ study investigators have NO knowledge about whether the study participant has been assigned to the treatment/ control (non treatment) group.
- a) single-blind = study participant does not know whether they are receiving treatment or no treatment
b) double-blind = neither the study participant nor the study investigator administering the treatment knows who is receiving treatment or no treatment
c) neither the study participant nor the study investigator administering the treatment nor the study investigator monitoring the effects of the treatment knows who is receiving treatment or no treatment
What is the placebo effect?
participants assigned to placebo group improve because they are TOLD that they will. This stems from the power of suggestion
- the goal of compliance in a study is to have groups be as _________ as possible on exposure and as ________ as possible on other important characteristics
- non-compliance is closer to the _____
- alike on exposure
different on other characteristics (age, sex) - null
- What is a randomized crossover trial?
- the biggest risk factor in randomized crossover trials is _________
- randomize so one group receives intervention then control, and the other receives control then intervention
- contamination
- What are cluster randomized trials?
- T/F: there is a higher risk of contamination in cluster randomized trials compared to randomized crossover trials
- an experimental study type where the unit of randomization is an entire group
- F. lower risk because the intervention doesn’t change between groups
