Discriminant function analysis

On 2008-02-07, Birgit Lemcke <birgit.lemcke at systbot.uzh.ch> wrote:

Am 06.02.2008 um 21:00 schrieb Tyler Smith:

My dataset contains variables of the classes factor and numeric. Is
there another function that is able to handle this?

The numeric variables are fine. The factor variables may have to be
recoded into dummy binary variables, I'm not sure if lda() will deal
with them properly otherwise.

But aren?t binary variables also factors? Or is there another
variable class than factor or numeric?
Do I have have to set the classe of the binaries as numeric?

There is no binary class in R, so you would have to use a numeric
field. For example:

| sample | factor_1 |
|--------+----------|
| A      | red      |
| B      | green    |
| C      | blue     |

becomes:

| sample | dummy_1 | dummy_2 |
|--------+---------+---------|
| A      |       1 |       0 |
| B      |       0 |       1 |
| C      |       0 |       0 |

R can deal with dummy_1 and dummy_2 as numeric vectors. The details
should be explained in a good reference on multivariate statistics
(I'm looking at Legendre and Legendre (1998) section 1.5.7 and 11.5).

HTH,

Tyler