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16 Cards in this Set
- Front
- Back
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what does the central limit theorum mean? |
the means of a simple random sample is approximately normal so the mean is the same as the population mean |
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what is the one sample t test? |
when you think you know a population mean from a theory |
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what are the 3 hypothesis? |
Ho= sample mean is some specified value two sided Ha- population mean is not equal to the value one sided Ha- specifies the direction ie less than |
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how is the standard deviation of the sample mean calculated? |
s/ squaroot of the number |
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how do you calculate t? |
sample mean- hypothesised mean / SE |
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what is the t statistic under random sampling? |
n-1 DF |
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what happens with large sampled? |
t and z are similar |
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when is a z test accurate? |
for large samples but works for any distruibution of data |
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WHEN are t tests accurate? |
most of the time providing data sets are normal. |
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what is the paired t test? |
measurements are matched in pairs some individuals before ans ome after the treatment |
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what is the null hypothesis for the paired t test? |
mean difference between two members of the pairs is 0 |
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how do you calculate the paired t test? |
estimate- value under Ho/ standardizing term. |
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what does the standardizing term do? |
similar job to the standard error in a single mean. it is larger when the sample standard deviation is larger or sample sizes are smaller. |
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what are the assumptions? |
simple random sampling normal distribution. |
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what is the two sample t test? |
refers to the sample sizes of two groups. |
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when is there a t distribution? |
a tdistribution if the heights in the two populations are(approximately) normally distributed |
