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32 Cards in this Set
- Front
- Back
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Relative risk =
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Iold/Inew
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Odds ratio=
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Oddsold/Oddsnew
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Absolute risk reduction
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Iold - Inew
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NNT =
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1/(Iold - Inew)
OR 1/ARR |
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What is efficacy? How is it calculated?
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how much of the risk in control group is reduced by the new treatment.
ARR/Iold |
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The odds ratio is an alternative to ___
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RR
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You can use relative or absolute measures of effect. Explain and when is each one useful.
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Relative are very informative for causation strength.
Absolute is very informative with regards to the total risk reduction associated with a treatment |
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Do relative or absolute measures measure the magnitude?
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absolute
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What allows you to compare both relative and absolute measures?
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efficacy
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Relative or absolute?
1. most relevant for etiology. 2. attributable risk. 3. most relevant to evaluate actual treatment/risk to exposed individuals. |
1. relative.
2. absolute 3. absolute |
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why can't you only analyze the treatment of actual treatment when there is crossover?
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violate principles of random
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besides upholding randomization, why is it important to use intention to treat for analysis?
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because crossover may be heavily due to adverse effects of treatment
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List the three main limitations of randomized clinical controlled trials.
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not always feasible of ethical.
limited generalizability. statistical uncertainty |
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what is an alternative to incidence? to relative risk?
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explain NNT.
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compare relative, absolute, and combination factors.
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think about when each is relative.
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good work.
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what is a parameter
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When you want to know if one treatment is better, you want to know by how much this treatment is better!
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is standard error bigger or smaller if you have a big sample size
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smaller
inverse relationship |
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describe type one error
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when you think there is a difference when in fact there is not
associated with false positive and p value |
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describe type II error
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when you think there is no difference when in reality there IS!
associated with false negative and beta probability |
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is type I or type II error more common? why?
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type I error is more common because there is only one null hypothesis and many alternative hypotheses!
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what is the null hypothesis in the case of ARR? In RR?
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0
1 |
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how do you account for type I error?
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in your pvalue
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give the wording for the p value
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the probability that the difference in our findings this large or larger from the null hypothesis would only occur __% of the time IF the null were in fact true
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in order to find your pvalue what do you do to z?
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you double it
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give a definition for confidence interval
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the range of values in which you would find your mean parameter 95% of the time
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what can the CI NOT include if you want to say your null is untrue
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you can't include your null hypothesis value
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what three things does statistical power depend on?
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magnitude of findings
set alpha value sample size |
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how do you caluclate chi square
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sum of ....(O-E)^2 / E
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how do you calculate SD?
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like this!
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how do you relate a p value and a z score?
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Find z. Double it. This is P!
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