pgf | R Documentation |
A function to draw an F distribution and shade a region defined by the quantile. Note that pgf only gives upper tail probabilities and upper tail shading of the relevant area under the curve.
pgf(quantile, df1 = 1, df2 = 5)
quantile |
The quantile value (F value) to be evaluated. |
df1 |
Numerator degrees of freedom for the F distribution. Note that the default is 1. |
df2 |
Denominator degrees of freedom for the F distribution. Note that the default is 25. |
This function can be very helpful in instructional situations and can replace the "F table" from textbooks.
Warning: Specifying extremely high quantiles may not yield visible shaded
areas if the quantile is in a region where the distribution approaches a
density of zero.
In addition, probabilities are rounded to five decimal
places and will display as zero if below .000005. Use the pf
function in this case.
Note that the pgf
function only displays upper tail
regions since most inference with the F distribution
only requires upper tail evaluation. The lower tail probability can be
found as 1 minus the returned upper tail probability.
Bruce Dudek bruce.dudek@albany.edu
pgf(3.75, df1=1,df2=25)
pgf(3.75, df1=2,df2=50)
pgf(3.75, df1=1,df2=125)
pgf(3.75, df1=6,df2=80)
pgf(4.11, df1=1,df2=18)
pgf(.65, df1=1,df2=25)
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