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31 Cards in this Set
- Front
- Back
what measures exactly how unusual the results of an experiment really are
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p-values
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the probability of rejecting a null hypothesis that is false
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power
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power depends on what 4 things?
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1. the degree to which the null hypothesis fails
2. significance level of the test 3. standard deviations 4. sample size |
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probability to detect a given difference from hypothesized value
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power
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as type I error decreases, type II error...
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increases
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proability of rejecting the null hypotheis when it is true
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type 1 error
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proability of accepting the null hypotheis when it is false
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type 2 error
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as sample size increases, power
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increases
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as the difference between means increases, power
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increases
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as variance decreases, power
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increases
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Test the null hypotheis, H0: u1=u2
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unpaired two-sample t-test
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Tests that the means of some variable are equal in two groups of subjects
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unpaired two-sample t-test
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Assumptions of unpaired two-sample t-test
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1. independent samples
2. normal distrubutions (in each group) 3. equal standard deviation |
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distribution and degrees of freedom for unpaired two-sample t-test
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t-distribution,DF= n1 + n2 - 2
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as the number of degree of freedoms increase, the t-distribution becomes...
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more normal
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tests the H0: uD = 0
Test the null hypothesis that mean difference between of some variable is 0 |
paired (one sample) t-test
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distrubtion and degree of freedome for paired t-test
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t-distribution
DF= n-1 |
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assumptions of paired t-test
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normal distribution
independent sample |
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Wilcoxon's test is an alternative to what test?
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paired t-test
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when do you use the wilcoxon's test
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when the assumptions for the t-test are not satisfied
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advantages of wilcoxon's test
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1. only required assumption is tha the samples are indepdent
2.robust! (outliers have little effect on results) |
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disadvantage of wilcoxon's test
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1. less powerful than t-test
2. confidence bounds not easily computed |
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which test of means is more powerful? t-test or wilcoxon's
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t-test
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assumptions for wilcoxon's test
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indepdendent samples
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when testing means, what are the parametric tests
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unpaired t-testpaired t-test
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when testing means, what is the non-parametric test
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wilcoxon's
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Tests the mean differences between more than
two groups |
ANOVA
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HO: u1=u2=u3
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ANOVA
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pros of ANOVA
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comparing more than 2 tests simultaneously
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cons of ANOVA
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diminishing returns! adding a factor adds a degree of freedom which decreases power
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the ANOVA is comprabile to what test
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unpaired t-tests
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