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75 Cards in this Set

  • Front
  • Back
What are the types of experimental studies?
1. Randomized Clinical trials
2. Open label trials
3. Cross-over trials
What are the types of observational studies?
1. Cohort
2. Case Control
3. Cross-sectional
4. Case reports
5. Case series
What is the goal of peer reviewed journals?
To minimize publication of articles that have flawed methods or are poorly written.
What are the advantages of primary literature?
1. Contains current, original, and "cutting-edge" information
2. Peer review process
What are the disadvantages of primary literature?
1. Consequences of flaws in study methodology
2. Need to have knowledge of study design and statistics to appropriately interpret the information
3. Often takes time for study results to be accepted into clinical practice
What are some characteristics of a reputable journal?
1. Peer-reviewed
2. Editorial board
3. Instructions for authors
4. Minimal to no advertisements
What is the purpose of the abstract?
It briefly presents an overview of the study. There should be enough information in the abstract to determine if the article is of any interest, however clinical decisions cannot be made based upon the abstract.
What is the most important section of an article?
The methods
If you don't understand this, then it will be difficult to understand the rest of the article.
Characteristics that patients had to meet to be entered into the trial.
Inclusion criteria
Characteristics that prevent a patients enrollment into the trial.
Exclusion criteria
Where should the results be interpreted?
They should be interpretted in the discussion.
Should the funding source be revealed in the article.
What is this study design?
-Subjects are assigned to an intervention by the study investigator
-Data is prospective
-The purpose is to determine a cause and effect relationship
Randomized controlled trial
What are the goals of a randomized controlled trial?
-equivalent sampling groups
-control the intervention
-obtain reliable measurements of the reponse
What are the advantages of RCT?
1. gold standard for efficacy trials
2. Causality
3. Less bias
What is the run-in period?
It is a pre-randomization period of observation used to determine adherence to therapy.
Type of blindness where subjects OR investigators do not know what group subjects have been assigned.
Type of blindness where both the study investigator AND subjects do not know what treatment a subject is receving.
STudy investigators adn subjects know what treatment the subject is receiving.
What is internal validity?
The "truth" about inferences made from a cause-effect relationship. How well potential sources of bias are eliminated.
What is external validity?
How your study applies to the rest of the world.
What is a crossover trial?
It is self controlled and subjects recieve both the treatmentAND the control.
When is a washout period needed?
During a crossover trial or N-of-1 trial when the treatment is being changed for the group.
What is a clinical trial involving only 1 person?
N-of-1 trial
Purpose of trial is to determine if the quality, safety, and efficacy of generic drugs differs by no more than a specific amount to brand name drugs. Conducted in healthy volunteers.
Bioequivalence studies
Purpose of study is to show that one treatment is not worse than another treatment or active control.
Non-inferiority trial
Study is based on presence or absence of a disease.
Compare outcomes of patients from naturally occuring exposures, treatments, characteristics.
Determine an association and NOT a causation
Observational study design
A population that can be enumerated (listed).
Subjects listed as exposed or unexposed.
No randomization of patients
Strongest t observational design.
Cohort Study
What are the advantages of a cohort study?
1. longitudinal
2. can measure incidence
3. can study multiple disease outcomes from a single study
What are the disadvantages of a cohort study?
1. inefficient for rare outcomes
2. length of follow-up
3. expensive
4. labor intensive
Case: subject with the outcome of interest
Control: subject without the outcome of interest
Cases and controls: need to be sampled from the same population
Case-control study
What are the advantages of Case-control studies?
-efficient for rare diseases
-appropriate for conditions that take years to develop
-can study multiple
What are the disadvantages of case-control studies?
1. maybe biased depending on how cases and controls are selected
2. may be difficult to assess exposure retrospectively
3. less confidence that exposure preceded the outcome
What is prevalance?
The number of people with the outcome of interest out of the total population
What is this type of study?
-Prevalence study
-snapshot in time
-meausurements are taken at a single point in time
Cross-sectional study
What are the advantages of cross-sectional study?
What are the disadvantages of cross-sectional studies?
-Difficult to know if exposure preceded outcome of interest
-transient effects
-prone to bias and confounding (selection bias)
What type of observational study design would be used to write up a report on a drug toxicity?
Case studies, case reports, case series.
Observational report on the clinical course of disease.
Provides information on sociologic and psychologic variables?
Survey Research
What types of bias are involved with Survey Research?
1. Sampling bias
2. Response bias
3. Measurement bias
4. Non-response bias
Combines results from other trials to formulate an overall conclusion.
Reviews the evidence AND provides a quantitative assessment.
Appropriate for both experimental and observational studies.
Phase of testing for a new drug or treatment.
Tested in a small group of healthy volunteers.
Evaluates safety, kinetics, side effects, not effecacy
Phase I
Phase tested in a larger group of patients (100s)
Evaluates efficacy and safety
Give to people with disease
Phase II
Phase tested in an even larger number of actual patients (100s to 1000s)
Evaluates efficacy, benefits, range of side effects.
If this phase is successful, the company can apply to FDA for approval.
Phase III
Post-marketing surveillance
Evaluates long term side effects, pharmacoeconomics
Phase IV
Claims there is no difference between the groups.
Null Hypothesis
Disagrees with the null hypothesis
Alternative hypothesis
Designed to detect deviation from the null hypothesis in only 1 direction.
One-tailed test
Appropriate if investigators have an explanation as to the outcome of the study.
Designed to detect deviations from null hypothesis in both directions.
Two-tailed test (non-directional)
Appropriate if investigators have no expectations as to the outcome of the study
Probability of incorrectly rejecting the null hypothesis when it is true.
Alpha value
usually 0.05 (5% chance)
Rejecting the null hypothesis when it is true.
Type I error
How does the p-value relate to the alpha value and the null hypothesis.
If the p-value is less than the alpha value, the null hypothesis is rejected.
Accepting the null hypothesis when it is actually false.
Type II error
What is the value relating to the probabability of comitting a type II error?
usually set at 20%
Variable which includes an outcome of interest which should change in response to intervention.
Dependent variable
Variable which includes the intervention, what is being manipulated.
Independent variable
Types of Data

-named categories with no implied order among the categories.
-can be dichotomous or multiple
-often described by proportions or percentages
-i.e. yes, no answers
Nominal Data
Types of Data

-data is ranked in specific order
-as move from one group to the next, it becomes "better"
-i.e. pain scale
Ordinal Data
Types of Data

-Equal distances between values
-arbitrary zero point
-differences between numbers are meaningful
-Ratios between numbers are NOT meaningful!!!
-i.e. celcius temperature scale
Interval Data
Types of Data

-equal distances between variables
-Meaningful zero point!!
-Differences AND ratios between numbers are meaningful
-i.e. HR and BP
Ratio Data
True or False?
Ratio and Interval Data can be grouped under the term "Continuous data"

Not treated differently from a statistical perspective
What is Parametric Data?
-collected from sample that can be described using a 'normal distribution'
-data is symmetrical, continuous, and forms a bell-shaped curve
-usually refers to interval or ratio data
What is Non-parametric data?
-collected from sample that is NOT normally distributed
-usually refers to nominal or ordinal data
Arithmetic average of the observations?
Interval and ratio data
X = mean
sensitive to extreme values
Value such that half of the observations fall above it, and half below it.
Value or category that occurs most frequently.
What is skewness?
Outlying observations occur in only 1 direction.
What are the 4 measures of dispersion?
1. Range
2. Percentiles/IQR
3. Standard deviation/variance
4. Standard error of the mean
What type of data can the range be used for?
Ordinal, Interval and Ratio (esp with skewed distribution)
What measure of distribution is often used to compare an individual with a norm?
What is the Interquartile Range?
It is the difference between the 25th and 75th percentiles or the middle 50 percent.
It is used for ordinal, interval, and ratio data
What is SD/variance used for?
Interval and Ratio data (symmetric)

It is sensitive to extreme values
What are the questions you should ask to determine which statistical test was used?
1. What type of data?
2. How many groups?
3. Is the data parametric or nonparametric
What statistical test is the non-parametric equivalent of ANOVA?
Kruskal-Wallis Test
What test is used to determine if there is an association between two variables?