Flashcards in L1 - Research methods and design Deck (19):
Describe the observational (epidemiological) research methodology
what are the different types?
Observational research is a type of correlational research in which a researcher observes ongoing behavior.
Particularly prevalent in the social sciences and in marketing.
It is typically divided into naturalistic (or “nonparticipant”) observation, and participant observation.
Naturalistic (or nonparticipant) observation has no intervention by a researcher. It is simply studying behaviors that occur naturally in natural contexts, unlike the artificial environment of a controlled laboratory setting.
In participant observation, the researcher intervenes in the environment. Most commonly, this refers to inserting himself/herself as a member of a group, aimed at observing behavior that otherwise would not be accessible. Also, behaviors remain relatively natural, thereby giving the measurements high external validity.
Case Studies are a type of observational research that involve a thorough descriptive analysis of a single individual, group, or event. They can be designed along the lines of both nonparticipant and participant observation.
Describe the Interventional (experimental) research methodology
what are the different types?
Interventional studies, also called experimental studies, are those where the researcher intercedes as part of the study design
Retrospective studies are those where data are collected from the __, either through records created at that time or by asking participants to remember their ______ or ___. Retrospective studies cannot demonstrate ______ as easily and are more prone to different ___, particularly ___ ____.
Retrospective studies are those where data are collected from the past, either through records created at that time or by asking participants to remember their exposures or outcomes. Retrospective studies cannot demonstrate temporality as easily and are more prone to different biases, particularly recall bias.
Prospective studies follow participants ______ through time, collecting data in the process. Prospective studies are less prone to some types of __ and can more easily demonstrate that the exposure preceded the ______, thereby more strongly suggesting _________.
Prospective studies follow participants forward through time, collecting data in the process. Prospective studies are less prone to some types of bias and can more easily demonstrate that the exposure preceded the disease, thereby more strongly suggesting causation.
describe a cross-sectional study
The defining feature of a cross-sectional study is that it can compare different population groups at a single point in time. Think of it in terms of taking a snapshot. Findings are drawn from whatever fits into the frame.
What are the positive and negative aspects of cross-sectional study
The benefit of a cross-sectional study design is that it allows researchers to compare many different variables at the same time.
BUT, they ususally show association, NOT causation
e.g we can’t know for sure if daily walkers had low cholesterol levels before taking up their exercise regimes, or if the behaviour of daily walking helped to reduce cholesterol levels that previously were high.
What are the positive and negative aspects of longitudinal studies
The benefit of a longitudinal study is that researchers are able to detect developments or changes in the characteristics of the target population at both the group and the individual level. The key here is that longitudinal studies extend beyond a single moment in time. As a result, they can establish sequences of events.
negatives = potential confounders
- need to be aware of your measurement tools and their limitations
Longitudinal studies can be _____or ________
Epidemiological - observing the natural history of disease
experimental - testing the behavoiur of the disease, interventional
beware of confounders
What is the RR, relative risk or risk ratio?
the ratio of the probability of an event occurring (for example, developing a disease, being injured) in an exposed group to the probability of the event occurring in a comparison, non-exposed group.
Relative risk is used frequently in the statistical analysis of binary outcomes where the outcome of interest has relatively low probability.
It is thus often suited to clinical trial data, where it is used to compare the risk of developing a disease, in people not receiving the new medical treatment (or receiving a placebo) versus people who are receiving an established (standard of care) treatment.
What is AR, Attributable risk
In epidemiology, attributable risk is the difference in rate of a condition between an exposed population and an unexposed population. Attributable risk is mostly calculated in cohort studies, where individuals are assembled on exposure status and followed over a period of time.
What are the types of population acquisitions?
Enriched - Enrichment is prospective use of any patient characteristic – demographic, pathophysiologic, historical, genetic, and others – to select patients for study to obtain a study population in which detection of a drug effect is more likely than it would be in an unselected population.
Enriched enrolment (the exclusion of non-responders or specific inclusion of responders) is believed to add both to trial sensitivity and to the measured effect of an intervention.
What is power?
he power of any test of statistical significance is defined as the probability that it will reject a false null hypothesis. Statistical power is inversely related to beta or the probability of making a Type II error (false negative)
The combination of biomarkers provides a better...?
new criteria in Alzheimers disease changes the senesitivity and specificity of disease markers
What are the benefits of new criteria for disease characterisation?
changes the sensitivity and specificty of biomarkers for detecting early disease
Alters the effect of intervention on outocme measure of disease conversion
Better characterise those with preclinical disease
We should have standardisated _______ _____ to allow identification of those at risk.
We should have standardisated biomarker reporting to allow identification of those at risk.
levels of certainty (e.g Mild congnitive impairment due to AD) can then help with disease staging (e.g Preclinical AD)
What are the challenges in identifying correctly those with disease and treating (i.e AD)
rater/assessor reliability can vary
poor sensitivity to detect decline in performance in healthy population
confounders, age, education, cultural differences
-alot we don't know
- is it reversible?
- role of comorbidity
What are the aspects of a good new criteria for disease diagnosis?
easy to use
terminology ethical to those who may never develop siase
include but not require biomarkers
one agreed set, clear cut off 1-1/5 STDEV
Terminology consistent with previously widely used definitions
Refined as indicated by data
What are the principles of early detection?