Statistics

• Normal distribution


  A bell-shaped distribution which has important role in inferential statistics
• Normal distribution


  • Provides 4 graphical representation of statistical value that are needed in describing the characteristics of population as well as in making decisions
• Normal distribution


  A continuous probability distribution described by normal equation f(x) = ±e's (14) 2
• Normal probability distribution

  • The distribution curve is bell shaped
  • The curve is symmetrical about its center
  • The mean, median, and mode coincide at the center
  • The tails of the curve flatten out indentinitely along the horizontal axis, always approaching the axis but never touching it (asymptotic to the base line)
  • The total area under the normal curve is equal to 1 or 100%
• Mean


  Determines the location of the center of the bell-shaped curve, a change in the value of the mean shifts the graph of the normal curve to the right or left
• Standard deviation


  • Determines the shape of the graph, particularly the height and width
  • Large value of standard deviation makes the normal curve short and wide
  • Small value of standard deviation yields skinnier and taller normal curve
• Finding Z-value

  1. Express the given Z-value into a three (3) digit number

  2. Using the Z-table, find the first two (2) digits on first column

  3. Find the 3rd digit on the 1st row on the right

  4. Read the area for the probability at the intersection of the row and column