# Doubts in applying Linear Regression

#1

Hi,

My data,

`````` Exercise Econ  Job Position
50    1    A    Owner
30    0 <NA>     <NA>
25    1    B Employee
44    1    B    Owner
32    0 <NA>     <NA>
50    0 <NA>     <NA>
22    1    A Employee
14    1    C Director
``````

`lm(formula = Exercise ~ Job + Position)`

The coefficients comes as
`Coefficients:`
`(Intercept) JobB JobC PositionEmployee PositionOwner`
`50 3 -36 -28 NA`

My Question is,

1. Why “NA” for PositionOwner ? and How do i resolve it ?
2. When i change the value to “C” for exercise “44” then i am not getting NA for postiionOwner ?
3. Generally, how can i dealt these NA in coefficents for factor variables ?

Regards,
Nantha.

#2

Actually the Formula is lm(formula = Exercise ~ Econ+Job + Position)

Data in formatted way,
Exercise Econ Job Position
50----------1-------- A--------Owner
30----------0-------NA-------NA
25----------1---------B-------- Employee
44----------1---------B-------- Owner
32----------0---------NA-------NA
50---------0-----------NA----------NA
22---------1----------NA----------Employee
14--------1-----------C----------- Director