curves and sampling distributions

chapter 6 lessons 1 and 2

EMPERICAL RULE (6.1)

For a distribution that is symmetrical and bell-shaped:


  • 68% of the data values will lie within 1 standard deviation on each side of the mean
  • 95% of the data values will lie within 2 standard deviations on each side of the mean
  • 99.7% of the data values will lie within 3 standard deviations on each side of the mean

Z SCORES (6.2)

  • the z value or z score (aka standard score) gives the number of standard deviations between the original meausrement x and the mean u of the x distribution