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8 Cards in this Set
- Front
- Back
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how to calculate the false positive ratio?
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1 - specificity
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how to calculate NNT?
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1 / ARR
ARR = Experimental Event Rate - Control ER |
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how is power of a study defined?
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probablity of a difference when there is one
power = 1 - beta (beta = type II error FINDING NO difference when one ACTUALLY exists) |
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what are chi-squared test, t-test, and ANOVA test for?
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chi-squared - comparing PROPORTIONS, how many fall into each category
t-test - comparing MEAN values ANOVA - comparing means of 3+ variables |
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how is the median calculated when there are an even # of data points?
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take the center 2 points and the median is halfway between them
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how to calculate the likelihood ratio?
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LR + = sensitivity / (1-specificity)
> 10 significantly increases likelihood pt will have dz for which tested positive |
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how to calculate confidence intervals?
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mean, SD, Z-score, sample size
first, calculate standard error of the mean (SEM) = SD / square root (n) multiply SEM by z-score z-score = 1.96 for CI 95%, = 2.58 for CI 99% so, for 95% CI = 1.96*SD/square root (n) |
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what is Berkson's effect? Pygmalion? Hawthorne?
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Berkson's bias - selection bias created by selecting hospitalized patients as control
Pygmalion effect - researches beliefs in efficacy of treatment that can potentially affect outcome Hawthorne effect - tendency of a study population to affect an outcome due to knowledge being studied |
