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22 Cards in this Set
- Front
- Back
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To compute the t statistic - single sample
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you must first calculate sample variance of standard deviation
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Population variance or standard deviation is unknown - what sc0
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T score used as a substitue for a z score that can not be computed when the population variance or standard deviation is unknown
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S squared
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Sample variance
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Sm
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Estimated standard error or sample variance
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S
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sample standard devistion
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t= (when )
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population variance or standard deviation is unknown
t=M-μ _____ Sm |
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σm is used when σ in unkown
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population
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ss
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sum of squared deviations of variability
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x-μ
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distance from mean
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ESTIMATE d
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C0HENS MEAN
measures effect size by computing the size of treatment in terms of standard deviation |
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r^2
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percentage of variane accounted for by the treatment effect
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estimated standard error
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An estimate of the standard error that uses the sample variance of standard deviation in place of the corresponding population value
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degrees of freedom df
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df-1
measures the number of scores that are free to vary when computing ss for sample data. the value of df also describes how well a statistic estimates a z=score |
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t-distribution
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The distribution of a t statistics is symmetrical and centered at zero like a normal distribution. A t distribution is flatter and more spread out than the normal distribution, but approached s a normal shape as df increases.
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t independent neasure
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df independent measures
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S independent measure
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s2p
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t distribution
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normal
flattened as d increases |
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As the vaLue of increases
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the t distribution becomes more normal to normal distribution
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Cohens effect size
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.01 small effect
.09 medium effect .25 large effect |
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d independent measure
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difference score for each individual X1-X2
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