> soil sample. So, for linear model, I need to work with that number

> or value. Now, R thinks that arcilla (arcilla means clay in

have an idea what you are calling your "y"-variable .... and it would

David.

>

> Residuals:

> Min 1Q Median 3Q Max

> -1.466e+01 -1.376e-15 1.780e-16 2.038e-15 1.279e+01

>

> Coefficients:

> Estimate Std. Error t value Pr(>|t|)

> (Intercept) 1.68964 6.33889 0.267 0.790221

> arcilla0.9 1.90228 8.90888 0.214 0.831239

> arcilla10 1.26371 7.96734 0.159 0.874212

> arcilla10.3 15.70081 9.05141 1.735 0.085090 .

> arcilla10.4 7.27517 7.72806 0.941 0.348183

> arcilla10.45 7.03879 9.02600 0.780 0.436853

> arcilla10.5 2.41241 8.90827 0.271 0.786954

> arcilla10.65 15.44298 9.03879 1.709 0.089838 .

> arcilla10.7 19.35651 9.04675 2.140 0.034185 *

> arcilla10.9 3.55947 9.18501 0.388 0.698974

>

> [...]

>

> arcilla9.9 6.31949 7.35724 0.859 0.391892

> arcilla#N/A 24.17959 8.87201 2.725 0.007274 **

> limo 0.24920 0.04605 5.412 2.76e-07 ***

> CO_gkg1 0.21015 0.03931 5.346 3.73e-07 ***

> C03Ca 0.01711 0.02727 0.628 0.531337

> ---

> Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

>

> Residual standard error: 6.249 on 135 degrees of freedom

> (50 observations deleted due to missingness)

> Multiple R-squared: 0.9736, Adjusted R-squared: 0.9014

> F-statistic: 13.47 on 370 and 135 DF, p-value: < 2.2e-16

>

> So, in the desired linear model, arcilla should be just a line, with

> the valors of the linear model.

> I hope you understand better more. If not, I could make an english

> version of the file to send, so you can try the commands.

> Thanks a lot for your help!

>

>

>

> Arantzazu Blanco Bernardeau

> Dpto de Química Agrícola, Geología y Edafología

> Universidad de Murcia-Campus de Espinardo

>

>

>

>

>

>

>

>

>

> ----------------------------------------

>> Date: Tue, 18 May 2010 11:54:20 -0400

>> Subject: Re: [R] (no subject)

>> From:

[hidden email]
>> To:

[hidden email]
>> CC:

[hidden email]
>>

>> Hi,

>>

>> Sorry, I'm not really getting what going on here ... perhaps having

>> more domain knowledge would help me make better sense of our

>> question.

>>

>> In particular:

>>

>> On Tue, May 18, 2010 at 11:35 AM, Arantzazu Blanco Bernardeau

>> wrote:

>>>

>>> Hello

>>> I have a data array with soil variables (caperf), in which the

>>> variable "clay" is factor (as I see entering str(caperf)) . I need

>>> to do a regression model, so I need to have arcilla (=clay) as a

>>> numeric variable. For that I have entered

>>>

>>> as.numeric(as.character(arcilla))

>>>

>>> and even entering

>>> 'as.numeric(levels(arcilla))[arcilla]'

>>

>> The above code doesn't make sense to me ...

>>

>> Perhaps cleaning up your question and providing some reproducible

>> example we can use to help show you the light (just describing what a

>> variable has isn't enough -- give us minimal code we can paste into R

>> that reproduces your problem).

>>

>> Alternatively, depending no what your "levels" mean, you might want

>> to

>> recode your data using "dummy variables" (I'm not sure if that's the

>> official term) .. this is what I mean:

>>

>>

http://dss.princeton.edu/online_help/analysis/dummy_variables.htm>>

>> In your example, let's say you have four levels for "clay" ... maybe

>> "soft", "hard", "smooth", "red"

>>

>> Instead of only using 1 variable with values 1-4, you would recode

>> this into 4 variables with values 0,1

>>

>> So, if one example has a value of "smooth" for clay. Instead of

>> coding it like:

>> clay: 3

>>

>> You would do:

>> soft: 0

>> hard: 0

>> smooth: 1

>> red : 0

>>

>> -steve

>> --

>> Steve Lianoglou

>> Graduate Student: Computational Systems Biology

>> | Memorial Sloan-Kettering Cancer Center

>> | Weill Medical College of Cornell University

>> Contact Info:

http://cbio.mskcc.org/~lianos/contact>

> _________________________________________________________________

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