Z-scores and the Normal Distribution

A good introduction to this topic is Thomson Higher Education's workshop on z-scores.

The normal distribution is a theoretical distribution but it allows us to make descriptive statements about a raw scores that are randomly sampled from empirical distributions that may be assumed normal.

The difference between theoretical and empirical distributions confuses you? Click here to compare the two.

The normal curve table allows us to determine the total area 1) above or below a score and 2)between two scores.

Click here to view David Lane's interactive calculators for the normal distribution.

Depending on the what is required by a normal curve problem, the area under the normal curve may be expressed as

• proportion of cases/respondents/students
• percentage of cases when multiplied by 100
• number of respondents when multiplied by N (sample size).
  

Click HERE to take the non-graded Self-test 2A. Click HERE to take the graded Self-test 2B. Click HERE to take the non-graded Self-test 3A. Click HERE to take the graded Self-test 3B.