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
)
f x
( )
Γ
df
1
+
(
)
/2
[
]
Γ
df
2
⁄
(
)
---------------------------------
=
1
x
2
/
df
+
(
)
df
1
+
(
)
/2
–
π
df
-------------------------------------------------
tpdf(
tpdf(
computes the probability density function (
) 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 (
)
is:
