Calculating P- value

Question

In ANOVA table , I got

$F$-statistic $=330.285$

degrees of freedom (df) due to regression $= 6$

Error degrees of freedom $= 9$

But i don't know how to calculate $p-$value ?

I have tried in R software as

pf ( 330.285, 6, 9, lower.tail = F )

[1] 1

But it doesn't match with the result which is actually .000

Where am i doing mistake ?

Walter · Accepted Answer · 2015-04-11 01:26:33Z

3

I tried the command you stated and got

> pf( 330.285, 2, 26, lower.tail = F )
[1] 3.294207e-19

which is very close to the value you are expecting.

answered Apr 11, 2015 at 1:26

Walter

1299 bronze badges

$\begingroup$ Please, see the edit . I've wrote wrong df in the first post. $\endgroup$
– ABC
Commented Apr 11, 2015 at 1:34
$\begingroup$ But also i am getting 1 in pf( 330.285, 2, 26, lower.tail = F ) . Why !!! $\endgroup$
– ABC
Commented Apr 11, 2015 at 1:36
1

$\begingroup$ It is still working: pf ( 330.285, 6, 9, lower.tail = F ) [1] 4.984053e-10 $\endgroup$
– Walter
Commented Apr 11, 2015 at 1:37
$\begingroup$ Try reinstalling your R and stats package $\endgroup$
– Walter
Commented Apr 11, 2015 at 1:39
3

$\begingroup$ ABC -- I bet you have defined F as a variable which it will then use. What happens when you do str(F)? ... to be safe, always type FALSE in full. $\endgroup$
– Glen_b
Commented Apr 11, 2015 at 1:46

| Show 1 more comment

mark999 · Accepted Answer · 2015-04-11 01:40:00Z

3

I'm guessing that the problem is that you have F defined as a variable. Try

pf(330.285, 6, 9, lower.tail = FALSE)

Let this be a lesson to you: use TRUE and FALSE, not T and F!

answered Apr 11, 2015 at 1:40

mark999

3,2882 gold badges25 silver badges31 bronze badges

$\begingroup$ Yes , you are absolutely right. I've defined F=330.285 and also wrote lower.tail=F . $\endgroup$
– ABC
Commented Apr 11, 2015 at 2:13

Add a comment |

2 Answers 2