Message-ID: <alpine.DEB.2.10.1504141037200.7327@sauron.Berkeley.EDU>
Date: 2015-04-14T17:40:13Z
From: Phil Spector
Subject: Wrong results from anova
In-Reply-To: <CAHLnndaKvr5nkHycpXBnLv9Q_RND7Wz=As+6Vnb-Lgt8KLE=FA@mail.gmail.com>
Li Li -
I belive it's a rounding error -- try setting
options(digits=8)
before displaying the output:
> summary(fit.Y)
Df Sum Sq Mean Sq F value Pr(>F)
sample.Y 3 2203 734 190706 <2e-16 ***
Residuals 8 0 0
---
Signif. codes: 0 ?***? 0.001 ?**? 0.01 ?*? 0.05 ?.? 0.1 ? ? 1
> summary(fit.Y)
Df Sum Sq Mean Sq F value Pr(>F)
sample.Y 3 2202.70 734.23 190706 < 2.2e-16 ***
Residuals 8 0.03 0.00
---
Signif. codes: 0 ?***? 0.001 ?**? 0.01 ?*? 0.05 ?.? 0.1 ? ? 1
- Phil Spector
Statistical Computing Facility
Department of Statistics
UC Berkeley
spector at stat.berkeley.edu
On Tue, 14 Apr 2015, li li wrote:
> Hi all,
> I have following data. When I perform an anova, the residual sum of
> square returns to be zero.
> But this is wrong, since we can hand calculate the RSS to be around 0.0308.
> Did anyone come across the same problem before? Any suggestions?
> Thanks.
> Hanna
>
>> ydata
> Y sample.Y
> 1 0.477 0.5
> 2 0.477 0.5
> 3 0.478 0.5
> 4 27.320 27
> 5 27.420 27
> 6 27.300 27
> 7 29.440 29
> 8 29.620 29
> 9 29.610 29
> 10 35.840 35
> 11 35.900 35
> 12 35.850 35
>> fit.Y <- aov(Y~sample.Y, data=ydata)
>> summary(fit.Y)
> Df Sum Sq Mean Sq F value Pr(>F)
> sample.Y 3 2203 734.2 190706 <2e-16 ***
> Residuals 8 0 0.0
> ---
> Signif. codes: 0 ?***? 0.001 ?**? 0.01 ?*? 0.05 ?.? 0.1 ? ? 1
>
> [[alternative HTML version deleted]]
>
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