TI-83 Plus Inferential Statistics and Distributions 427
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:
df
dfx
df
df
xf df
π
2/)1(
2)/1(
)2/(
]2/)1[(
)( +−
+
Γ
+Γ
=
tpdf(x,df)
Note: For this example,
Xmin = L4.5
Xmax = 4.5
Ymin = 0
Ymax = .4
tcdf(
tcdf( computes the Student-t distribution probability between lowerbound
and upperbound for the specified df (degrees of freedom), which must be
> 0.