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ANOVA
Hypothesis testing with z, t and F scores  describe the logic of when we reject the null
hypothesis
ftest: when variance is greater than one
ttest: when observed is more extreme than critical
Z test: when observed is more extreme than critical
What is a point estimate?
 Describe the pros and cons relative to confidence intervals
Pro: make comparisons Con: they are just sentiments
 Point estimates are a more specific estimation, but less likely to be exactly right
 Confidence intervals are more general (range of scores), but more likely to include the best
estimate of the population parameter
Confidence intervals
 Describe what they are for? Say how confident you are
 We can be reasonable confident that the population mean falls within this range 1115 (with
either 95% or 99% confidence)
X
±
(z)(
σ
) SEE LAST PAGE FOR EXAMPLE
Describe the factors will affect the size of a confidence interval
(especially variability, sample size and confidence level)
More variability less confidence and bigger range, same with large sample sizes.
Describe how we can make our confidence interval smaller?
 decrease variability by decreasing random error (gather data carefully)
 decrease variability by using a more homogeneous sample (note: problem with
generalizability)
 decrease level of confidence
Level of significance (alpha = α)
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 Spring '08
 Delaney

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