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24 Cards in this Set
- Front
- Back
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CI, what does your mean represent? |
Point Estimate |
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How would you interpret a confidence interval? |
We are 95% confident that the interval from ____ to ____ captures the true mean/proportion (context)... |
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What's the formula for point estimate? |
A+B/2 |
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What's the formula for margin of error? |
B - point estimate |
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How do you get your interval? |
Point estimate +/- margin or error |
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How do you know if the value is valid? |
If it's in the interval provided |
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CL, how would you interpret a confidence level? |
If we were to select many random samples from the population and construct a C% confidence interval from each sample, about C% of the intervals would capture the true mean/ proportion |
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If the confidence level increases... |
The margin of error / interval increases |
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If the sample size increases... |
The margin of error/ interval decreases |
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What factors contribute or affect margin of error? |
Undercoverage - group of ppl not being represented Nonresponse - choose not to participate Response - lie about response |
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For estimating a proportion, what are the following conditions? |
Random, large counts, 10% |
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What's the formula for large counts |
np > 10 and n(1 - p) > 10 |
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How do you find the critical values or z*? |
1 - CI / 2 then go to invnorm |
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How do you find the CI using point estimate and margin of error? |
p hat ± z* p hat (1 - p hat)/n (square rooted) |
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When finding CI for a proportion, what's the formula for margin of error? |
Z* p hat (1-p hat)/n (square rooted) |
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If no value is given for p hat, then what would you use? |
0.5 |
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When constructing a confidence interval for u, what are the conditions? |
Random, 10%, and CLT |
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Why do we use CLT? |
See if population is approx normal Sample data shows no strong skew or outliers |
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When do you use t* |
For means |
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What's degrees of freedom |
n-1 |
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If df isn't on the table.... |
Round the value down |
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When finding one sample t interval for u, what's the formula? |
mean ± t* x standard deviation / square root of n |
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How do you find margin of error w sample sizes? |
t* x standard deviation / square root n |
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If you don't have the sample size or the z*, what do you use for z* on the table? |
infinity |
