Rebecca Wallace

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Chapter 10

• By
• Rebecca Wallace
• and
• Michelle Fortuno

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• BUM BUM BUMMMMMMMM.

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Estimating with Confidence

• Confidence Interval the interval of numbers
  between values
• CI estimate ? margin of error
• Margin of error decreases as
• confidence level C decreases
• population standard deviation ? decreases
• sample size n increases

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• Confidence Interval has two parts
• interval computed from the data
• confidence level gives the probability that the
  method produces an interval that covers the
  parameter (gives a correct answer)
• To find a CI for a population mean with a sample
  size n, having unknown mean ?, and known standard
  deviation ?

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To determine the sample size required to obtain a
CI with a specified margin of error
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Helpful Calculator Keystrokes!

• STAT gtTest 7
• this will show you the way to determine the
  z-test results

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Tests of Significance

• Test of significance evaluates the evidence
  given by the data
• Null hypothesis Ho there is no effect or change
  in the population
• Alternative hypothesis Ha there is an effect or
  change in the population

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• P-value the probability computed supposing Ho
  to be true (that the test statistic will take a
  value at least as extreme than that actually
  observed)
• the smaller the P-value, the stronger the
  evidence against Ho
• if the P-value is as small or smaller than ?,
  it is statistically significant at level ? (not
  likely to happen just by chance)
• ex
• ? .05 p .03 ? .01 p .03
• p lt ? .03 lt .05 OR p lt ? .01lt .05
• statistically significant not significant
• at ? .05 at ? .01

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WAKE UP!

• Dont worry. Were almost done. Really. We
  are. Sooooo. Pay attention. This is valuable
  information.

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Tests for a population mean

• 1. State the hypotheses
• 2. Calculate the test statistic
• 3. Find the P value
• 4. Analyze

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To find a CI for a population mean with a sample
n, having unknown mean ?, and known standard
deviation ?
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Inference as Decision

• Type I error reject Ho (accept Ha) when in fact
  Ho is true
• Type II error accept Ho (reject Ha) when in
  fact Ha is true
• Power of the test
• measures its ability to detect an alternative
  hypothesis
• power against a specific alternative is the
  probability that the test will reject Ho when Ha
  is true

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Note to Mrs. Hathaway

• Hi Mrs. Hathaway!!! Whew! This power point
  took us a while. Yes indeed because we are not
  power point literate. BUT we did it! YEAY)
  The Blimpy commercial says that you remember
  things better the more times you see it.
  Soooummm look
• AAAAAAAAAAAAAAAAA
• okay. Thats all. Was it good? We hope so.

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THE END...