[R] Fw: How I can calculate the value of response variable

[rezvan hatami]

----- Forwarded Message -----
 From: rezvan hatami <rezvan.hatami_iut at yahoo.com>
 To: David Winsemius <dwinsemius at comcast.net> 
 Sent: Monday, 27 June 2016, 9:44
 Subject: Re: [R] How I can calculate the value of response variable
   
Dear DavidThank you for your answer. My equation is:
nitrate=0.9*fertilizer-0.02*flowrate+0.5*rain
my matrix:
| season | site | nitrate | fertilizer1 | flow rate |
| spring | site1 | 0.2 | 2 | 1 |
| spring | site2 | 1.2 | 3 | 1 |
| spring | site3 | 2.2 | 5 | 2 |
| summer | site1 | 3.2 | 1 | 2 |
| summer | site2 | 4.2 | 2 | 2 |
| summer | site3 | 5.2 | 3 | 2 |
| fall | site1 | 6.2 | 4 | 3 |
| fall | site2 | 7.2 | 5 | 3 |
| fall | site3 | 8.2 | 6 | 3 |
| winter | site1 | 9.2 | 4 | 4 |
| winter | site2 | 10.2 | 8 | 4 |
| winter | site3 | 11.2 | 9 | 4 |


I would like to know, what will be the values for variable "nitrate" if I divide the values of fertilizer by half and change the equation to:
nitrate=0.9*fertilizer2-0.02*flowrate+0.5*rain

in a matrix like:

| season | site | nitrate | fertilizer2 | flow rate |
| spring | site1 | 0.2 | 1 | 1 |
| spring | site2 | 1.2 | 1.5 | 1 |
| spring | site3 | 2.2 | 2.5 | 2 |
| summer | site1 | 3.2 | 0.5 | 2 |
| summer | site2 | 4.2 | 1 | 2 |
| summer | site3 | 5.2 | 1.5 | 2 |
| fall | site1 | 6.2 | 2 | 3 |
| fall | site2 | 7.2 | 2.5 | 3 |
| fall | site3 | 8.2 | 3 | 3 |
| winter | site1 | 9.2 | 2 | 4 |
| winter | site2 | 10.2 | 4 | 4 |
| winter | site3 | 11.2 | 4.5 | 4 |


Would you please tell me how I can do this in R?
Cheers
Rezvan
      From: David Winsemius <dwinsemius at comcast.net>
 To: rezvan hatami <rezvan.hatami_iut at yahoo.com> 
Cc: "r-help at r-project.org" <r-help at r-project.org>
 Sent: Monday, 27 June 2016, 1:20
 Subject: Re: [R] How I can calculate the value of response variable
  

> On Jun 26, 2016, at 3:23 AM, rezvan hatami via R-help <r-help at r-project.org> wrote:
> 
>  How I can calculate the value of response variable in a linear model of a matrix of several variables?Can somebody please answer me?
> 

  You should explain in more detail why the answer to this question is not just the `lm` function. See:

?lm
?predict.lm

    That would deliver (after suitable invocation of the `predict` function) not be the "value of the response variable" (since that would just be the values in your data), but rather the conditional expectation of the response variable given the values of the predictors.


> 
> Cheers
> Rezvan Hatami
>     [[alternative HTML version deleted]]
> 
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David Winsemius
Alameda, CA, USA


   

  
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