Inferential statistics:

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Inferential statistics

• 1. Techniques for making generalizations from
  samples.

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Hypothesis testing

• 1. Determining if the sample is representative
  enough of the population so that an inference can
  be made.

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5-step process for refuting chance (sampling
error)

• 1st. Identify the characteristics of data
  collected, I.e., variables

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2nd State your hypothesis

• (a) research or alternate hypothesis, i.e., the
  expected relationship
• (b) null hypothesis, i.e., statement of no
  relationship, no association, or independence

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3rd Select sampling distribution

• Use a Z distribution, whenever N is greater than
  120
• Use a t distribution whenever N is 120 or less
• 3. Use a one-tail testif the direction of the
  difference can be predicted
• 4. Use a two-tailed testif direction cannot be
  predicted

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4th calculate test statistic

• Calculate the outcome for your sample, e.g.,
  regression, chi-square etc.

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Level of Significance

• The probability of drawing by chance an unlikely
  sample outcome. You can set the alpha at any
  level, but the convention is to set at .01 or .05
• 2. Alpha .01 means 1 out of 100
  samples(times) you would be wrong to conclude
  that the sample differs from the population
• 3. Alpha .05, i.e., 5 out 100 samples, etc

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Critical region

• 1. Rejection region. Once alpha level is
  selected, you can determine the sample outcome
  that begins the critical region by using the
  table--

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5th make decision on null and research hypotheses

1. Decision on Ho
2. Reject a null hypothesismeans chance of
   an incorrect decision, I.e., type 1 erroris
   equal to the alpha level you have selected
3. accept (fail to reject) means chance of
   type 2 error

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Decision on research on research hypothesis

• 1. Ha is there a statistically significant
  difference?
• yes no
• reject
• accept
• If you accept then you can conclude that there is
  a statistically significant difference
• 2. Note you would either conclude that the
  sample is or is not representative of the
  population from which it was drawn. Implications--