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rnormal-distribution

R: how to find x given the value of qnorm(x)=-2

Given the value of qnorm(x)=-2, how to find x using R? I'm trying to solve the power 1-beta from the value of qnorm(1-beta). Thank you.

Solution

  • The pnorm function serves as the inverse for qnorm. Ergo

    > pnorm(qnorm(0.5))
[1] 0.5

    So to your question

    > pnorm(-2)
[1] 0.02275013
> qnorm(0.02275013)
[1] -2
> 1 - pnorm(-2)
[1] 0.9772499