[edit] Summary

[edit] Discussion

What is the z-score which has the steepest points of the curve? My guess it is z = -1, +1. The way to tell is to differentiate the pdf and find its maxima, but not sure if I'm up to that...

Is the 1.98 sigma/z-score for 95th percentile a typo? 1.96 is nearer 95% than 1.98 which corresponds to 95.2269%...

Y axis stands not for probability, as stated, but rather for probability density. Probability itself is zero for each given point. I think this is the important point.

If you want the probability within some interval, you would calculate the integral from one endpoint to the other. With the Normal Distribution, there is no elementary anti-derivative, so the values are calculated using numerical methods. This is why you usually refer to a table that contains the calculated values. In order to use the tables you must first calculate the z-score.

[edit] License information

This image has been (or is hereby) released into the public domain by its author, Heds 1 at the wikipedia project. This applies worldwide. In case this is not legally possible: Heds 1 grants anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law. العربية | Català | Česky | Dansk | Deutsch | Ελληνικά | English | Eesti | Suomi | Français | עברית | Italiano | 한국어 | Lietuvių | Македонски | Plattdüütsch | Nederlands | Polski | Română | Русский | Српски / Srpski | Svenska | ไทย | Vèneto | 中文 | ‪中文(简体)‬ | ‪中文(繁體)‬ | +/−

[edit] Original upload log

(All user names refer to en.wikipedia)

• 2007-07-12 14:47 Heds 1 800×600×0 (123727 bytes) A re-drawn chart comparing the various grading methods in a normal distribution. Includes: Standard deviations, cumulative percentages, percentile equivalents, Z-scores and T-scores. Inspired by Figure 4.3 on Page 74 of Ward, A. W., Murray-Ward, M. (1999)
• 2007-07-12 14:44 Heds 1 800×600×0 (137472 bytes) The re-drawn chart comparing the various grading methods in a normal distribution. Includes: Standard deviations, cumulative percentages, percentile equivalents, Z-scores and T-scores. Inspired by Figure 4.3 on Page 74 of Ward, A. W., Murray == Licensing == {{PD-self}} [[Category:Normal distribution]] {{subst:Unc}}

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current	10:48, 23 September 2007		800×600 (121 KB)	Abdull	({{Information |Description=The re-drawn chart comparing the various grading methods in a normal distribution. Includes: Standard deviations, cumulative percentages, percentile equivalents, Z-scores and T-scores. Inspired by Figure 4.3 on Page 74 of Ward, )

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