Lecture 6 Sep' 19, 2005

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Lecture 6 Sep. 19, 2005

• Dispersion
• Qualitative vs. Quantitative Research

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2 types of descriptive (summary) statistics (p.
264)

• Central Tendency determines the typical score of
  a distribution. Ex) mode, median, mean
• Dispersion describes the way the scores are
  spread out about the central point.
• Data set can be described adequately by
  reporting central tendency and dispersion

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Dispersion (pp. 264-265)1. Range

• Range the difference between the highest and
  lowest scores in a distribution of scores
  (simplest measure of dispersion)
• Formula R Xhi Xlo
• Ex) 20, 12, 11, 9, 5, 5, 3

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2. Variance

• Variance the degree to which scores deviate from
  the mean.
• Formula S2
• Computation
• 1. The mean is subtracted from each score
  (deviation scores)
• 2. The deviation scores are squared
• 3. The squares are summed and divided by N 1
• Ex) 10, 7, 5, 2, 1

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3. Standard Deviation

• Inconvenience of Variance Expressed in terms of
  squared deviations from the mean rather than in
  terms of the original measurement -gt Take the
  square root of the variance -gt Standard Deviation
  (SD)
• SD is more meaningful as it is expressed in the
  same units as the measurement used to compute it.

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• SD a given distance of a score from the mean of
  a distribution (best description of dispersion)
• Formula s
• Ex) 10, 7, 5, 2, 1

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Qualitative vs. Quantitative Research (pp. 48-50)

• Qualitative
• Methods of Data Collection focus groups, field
  observation, in-depth interviews, case studies
• The variables in qualitative research may or may
  not be measured or quantified.

• Quantitative
• Methods of Data Collection telephone surveys,
  mail surveys, Internet surveys
• Quantitative research requires that the variables
  under consideration be measured

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• Qualitative research
• concentrates on words and observations to express
  reality and attempts to describe people in
  natural situations
• provides in-depth information into fewer cases

• Quantitative research
• grows out of a strong academic tradition that
  places considerable trust in numbers that
  represent opinions or concepts
• allows for more breadth of information across a
  larger number of cases.

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Advantages

• Qualitative
• It allows a researcher to view behavior in a
  natural setting
• It can increase a researchers depth of
  understanding of the phenomenon under
  investigation
• It is flexible and allows the researcher to
  pursue new areas of interest

• Quantitative
• The use of numbers allows greater precision in
  reporting results
• It uses bigger samples of subject than
  qualitative research
• So, results can be generalized to the population
• Objectivity

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Disadvantages

• Qualitative
• Sample sizes are too small to allow the
  researcher to generalize the data beyond the
  sample selected for the particular study (often
  preliminary step)
• Loss of objectivity (understanding)

• Quantitative
• Advantages of qualitative research

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Relationship Between Qualitative and Quantitative
Research

• Qualitative and quantitative methods have a
  complementary role.
• Increasingly, researchers are recognizing the
  benefits of combining qualitative and
  quantitative procedures
• Triangulation the use of both qualitative and
  quantitative methods to fully understand the
  nature of a research problem