Measures of dispersion

• What is meant by measures of dispersion?

  Spread of scores
• what is meant by spread of scores?

  how far scores vary from another
• what is included in measures of dispersion?

  range and standard deviation
• why do we add 1 when calculating range?

  allows for the fact that raw scores often rounded up or down,so, it accounts for this margin of error
• why may range be unrepresentative

  only takes into account the 2 most extreme values
• what is standard deviation?

  single value that tells us how far scores deviate from the mean.
• what happens with a larger standard deviation?

  greater the dispersion within a set of data
• what can a large standard deviation imply, in terms of experiments?

  not all participants affected by IV in the same way
• what does a low standard deviation mean?

  data tightly clustered around mean
• what does a low stnadard deviation mean in terms of experiment?

  implies all participants responded in a fairly similar way
• why can standard deviation be distorted by extreme values?

  Includes all values