Statistical Analysis Part II

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Statistical AnalysisPart II
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• Graph the following data
• Individual Bowling Score
• 1 220
• 2 121
• 3 117
• 4 88
• 5 201
• 6 134
• 7 99
• 8 106
• 9 112
• 10 109

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Error Bars

• Can use range, standard deviation, or standard
  error

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Inserting Error Bars using Excel

• The data boxes for this will accept a data
  range. For example, if you have your data in 3
  columns X values, Y values and Y errors - you
  can use the third column to define the error bar
  extent for the data series.
• You must indicate the SHEET in which the values
  are located. For example, if your SEM values are
  in SHEET1, then enter in the custom box
  sheet1!c1c4
• After clicking the data series, and then
  clicking on the Error Bars tab, I click in the
  custom box (leaving the cursor there). Then,
  using the mouse, click and drag in the worksheet
  containing the error bar values, to highlight
  them. Drag the mouse over the cells containing
  the error values, the range will appear in the
  custom box. Return the mouse to the custom box
  and click OK. This gives me the error bars on the
  graph.

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Create Error Bars On Your Graph

• Results

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• t-test
• Used to test for a difference between two means.
• Example If two different groups or mice are fed
  different diets, and their growth rates are
  measured, the t-test can be used to find whether
  there is a significant difference between the
  growth rates with the two different diets.

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1 vs 2-tailed t-testd

• 1-tailed

• 2-tailed

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T-test example

• Example page 364

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t-test table of significant values

• A difference in means is considered
  statistically significant if the probability of
  it being due to random variation is 5 or less