Chapter 13: Inferential Statistics and Distributions 243
normalcdf(lowerbound,upperbound[,m,s])
invNorm(
invNorm( computes the inverse cumulative normal distribution function for a given area under the
normal distribution curve specified by mean m and standard deviation s. It calculates the
x value
associated with an
area to the left of the x value. 0 area 1 must be true. The defaults are m=0 and
s=1.
invNorm(area[,m,s])
invT(
invT( computes the inverse cumulative Student-t probability function specified by Degree of
Freedom, df for a given Area under the curve.
invT(area,df)
x()
Γ df 1+()/2[]
Γ df 2⁄()
---------------------------------=
1 x
2
/df+()
df 1+()/2–
πdf
-------------------------------------------------
tpdf(
tpdf( computes the probability density function (pdf) for the Student-t distribution at a specified x
value.
df (degrees of freedom) must be > 0. To plot the Student-t distribution, paste tpdf( to the Y=
editor. The probability density function (
pdf) is:
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