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by Gary H. McClelland

Working with z-scores and Normal Probabilities

This applet converts between raw scores and z-scores with a display of various areas of probability.

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Use this graph to calculate z-scores and to see the corresponding probabilities. Any number can be changed, but the change will not be effective until you press the return key while in one of the boxes. You may also change the portion of the normal distribution selected:

  • Cumulative--from minus infinity to the z-score
  • One-Tailed--from the z-score to positive infinity
  • Two-Tailed--absolute scores more extreme (i.e., further from the middle) than the z-score
  • Middle--absolute scores less extreme (i.e., closer to the middle) than the z-score
Note: If the graph does not update after hitting Return, re-select the graph type and it will update.
    Return to Seeing Statistics Normal Probability Examples
WARNING: The graph above gives accurate normal probabilities suitable for educational purposes such as homework problems. It is not intended for and should not be used for any calculations which have any major consquences for health, safety, financial matters, etc.

The above applet is from the section "Working with the Normal Distribution" in Seeing Statistics by Gary McClelland. For more information, visit Seeing Statistics

© 1999, Duxbury Press