Is this quarter fair?

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New Step

• Should add a new page
• Determine if
• One-sample t-test
• Two-sample t-test
• If it is a dependent samples design
• If it is a independent samples with equal N
• If it is a independent samples with unequal N

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Thus, there are 4 different kinds of designs

• Each design uses slightly different formulas
• You should probably make up ONE cook book page
  (with all 7 steps) for each type of design
• Will help keep you from getting confused on a test

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• My teacher is an idiot!
• You wonder if the professors at Villanova are
  more intelligent than the average person. To
  examine this you collected data from 4 of your
  teachers. Determine if Villanova professors
  really have significantly (? .05) higher IQs
  than the average IQ of the general population (?
  100).

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Data
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Step 1 Write out Hypotheses

• Alternative hypothesis
• H1 ?Prof gt 100
• Null hypothesis
• H0 ? Prof lt or 100

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Step 2 Calculate the Critical t

• N 4
• df 3
• ? .05
• tcrit 2.353

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Step 3 Draw Critical Region
tcrit 2.353
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Step 4 Calculate t observed

• tobs (X - ?) / Sx

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Step 4 Calculate t observed

• tobs (X - ?) / Sx

Sx S / N
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Step 4 Calculate t observed

• tobs (X - ?) / Sx

14.7329.45 / 4
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Step 4 Calculate t observed

• tobs (X - ?) / Sx
• 2.44 (136 - 100) / 14.73

1.1814.4 / 150
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Step 5 See if tobs falls in the critical region
tcrit 2.353
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Step 5 See if tobs falls in the critical region
tcrit 2.353
tobs 2.44
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Step 6 Decision

• If tobs falls in the critical region
• Reject H0, and accept H1
• If tobs does not fall in the critical region
• Fail to reject H0

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Step 7 Put answer into words

• We reject H0 and accept H1.
• Professors at Villanova have significantly (?
  .05) higher IQs than the average IQ of the
  general population (? 100).

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Practice

• 10.15
• Determine whether or not people respond to
  auditory and visual stimuli differently
• Alpha .05

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• t crit (6df) 2.447
• t obs -2.24
• Fail to reject Ho
• People do not respond to auditory and visual
  stimuli differently.

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Practice

• 10.30
• Are surgeons who have been sued more likely to
  sound dominating than surgeons who have not been
  sued?
• Alpha .05

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• t crit (15) -1.753
• t obs -2.16
• Accept H1
• Surgeons who sound dominating are more likely to
  be sued (alpha .05) than other surgeons.

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