[R-sig-eco] anova

[Chris Howden]

Post hoc comparisons such as tukey compare between groups.

U have to tell R that station is a grouping variable i.e. station needs to
be a factor. I'm guessing U have entered station as a number, meaning R
thinks it’s a continuous variable like temperature.

The give away is the 1 DF for station in your ANOVA table.

I suggest u convert station to a factor like so:

stationf <- factor(station)

and then fit the model

aov(zoo~stationf)


Chris Howden B.Sc. (Hons) GStat.
Founding Partner
Evidence Based Strategic Development, IP Commercialisation and Innovation,
Data Analysis, Modelling and Training
(mobile) 0410 689 945
(fax) +612 4782 9023
chris at trickysolutions.com.au




Disclaimer: The information in this email and any attachments to it are
confidential and may contain legally privileged information. If you are
not the named or intended recipient, please delete this communication and
contact us immediately. Please note you are not authorised to copy, use or
disclose this communication or any attachments without our consent.
Although this email has been checked by anti-virus software, there is a
risk that email messages may be corrupted or infected by viruses or other
interferences. No responsibility is accepted for such interference. Unless
expressly stated, the views of the writer are not those of the company.
Tricky Solutions always does our best to provide accurate forecasts and
analyses based on the data supplied, however it is possible that some
important predictors were not included in the data sent to us. Information
provided by us should not be solely relied upon when making decisions and
clients should use their own judgement.

-----Original Message-----
From: r-sig-ecology-bounces at r-project.org
[mailto:r-sig-ecology-bounces at r-project.org] On Behalf Of Mahnaz Rabbaniha
Sent: Thursday, 28 February 2013 6:05 PM
To: r-sig-ecology
Subject: [R-sig-eco] anova

Dear all

hi
may be my question is very basically:


I want to compare between zooplankton density in 36 station.

In base of shapiro.test and normality of data, i choose anova but when
apply TukeyHSD i take mis message.

any person help me what is meaning??




































































































































































> shapiro.test(f)

        Shapiro-Wilk normality test

data:  f
W = 0.9081, p-value = 0.1084

> model1<-aov(zoo~STATION)
> summary(model1)
                   Df     Sum Sq           Mean Sq        F      value
Pr(>F)
STATION       1     1.2055e+09     1205487359  0.3803 0.5384
Residuals   157 4.9771e+11 3170152766

> TukeyHSD(model1)
Error in TukeyHSD.aov(model1) : no factors in the fitted model In
addition: Warning message:
In replications(paste("~", xx), data = mf) : non-factors ignored: STATION
>

--
Mahnaz Rabbaniha
marine ecology PhD
Iranian Fisheries Research Organization (IFRO)
P.O.Box: 14155-6116 , P.Code: 1411816618* Tehran, IRAN
Phone:   +98 21 44580953
Fax:       +98 21 44580583
Mobile:  +98 912 5790377

	[[alternative HTML version deleted]]

_______________________________________________
R-sig-ecology mailing list
R-sig-ecology at r-project.org
https://stat.ethz.ch/mailman/listinfo/r-sig-ecology