Introduction to Statistics (MAT/SST 115.03 2008S)
Primary: [Front Door] [Syllabus] [Current Outline] [R] - [Academic Honesty] [Instructions]
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The standard normal probabilities table is essential to a host of statistical computations. As you know, that table gives the area under the standard normal curve to the left of a particular z-score.
We also use the table “backwards”: If we know a probability, we can use it to compute a corresponding z-score.
In R, you use pnorm
to go from
z-score to probability and
qnorm
to go back again.
>
pnorm(0)
[1] 0.5
>
pnorm(-1)
[1] 0.1586553
>
pnorm(-2)
[1] 0.02275013
>
pnorm(-3)
[1] 0.001349898
>
pnorm(1)
[1] 0.8413447
>
pnorm(2)
[1] 0.9772499
>
pnorm(3)
[1] 0.9986501
>
qnorm(.50)
[1] 0
>
qnorm(.25)
[1] -0.6744898
>
qnorm(.10)
[1] -1.281552
>
qnorm(.99)
[1] 2.326348
Primary: [Front Door] [Syllabus] [Current Outline] [R] - [Academic Honesty] [Instructions]
Groupings: [Applets] [Assignments] [Data] [Examples] [Handouts] [Labs] [Outlines] [Projects] [Readings] [Solutions]
External Links: [R Front Door] [SamR's Front Door]
Copyright (c) 2007-8 Samuel A. Rebelsky.
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