Dear List and Frank,
I have calculated the log-odds for my models but maybe i am not getting
something but i am not understanding how for a categorical factor this helps?
On all the examples i have see it relates to continuous factors where moving
from one number to another shows either a increase or decrease, not as in my
case a change of catagory.
Furthermore, this gives the values for each factor independent of each other,
how do i get the log-odds for the entire model? I appreciate i maybe trying to
put things in boxes again, i am not i am happy to report the log odds of
moving from one response level to the next but would like it for all the
factors together not independently.
John
Low High Diff. Effect S.E. Lower Upper
WO Woody:Non_woody 1 2
NA 0.28 0.16 -0.04 0.6
Odds Ratio 1
2 NA 1.32 NA 0.96 1.82
PD Abiotic:Biotic 2
1 NA -1.21 0.13 -1.47 -0.96
Odds Ratio 2
1 NA 0.3 NA 0.23 0.38
ALT All:Low 3
1 NA 0.47 0.19 0.11 0.84
Odds Ratio 3
1 NA 1.6 NA 1.11 2.31
ALT High:Low 3
2 NA -0.07 0.14 -0.35 0.21
Odds Ratio 3
2 NA 0.93 NA 0.7 1.24
ALT Mid:Low 3
4 NA 0.39 0.15 0.1 0.67
Odds Ratio 3
4 NA 1.48 NA 1.11 1.96
REG Two_plus:One 1 2
NA -0.59 0.13 -0.84 -0.34
Odds Ratio 1
2 NA 0.55 NA 0.43 0.72
BIO Arctic:Subtropical/Tropical 4
1 NA -1.02 0.81 -2.61 0.58
Odds Ratio 4
1 NA 0.36 NA 0.07 1.78
BIO Boreal:Subtropical/Tropical 4 2
NA -1.21 0.81 -2.79 0.37
Odds Ratio 4
2 NA 0.3 NA 0.06 1.44
BIO Mediterranean:Subtropical/Tropical 4 3
NA -1.89 0.48 -2.83 -0.95
Odds Ratio 4
3 NA 0.15 NA 0.06 0.39
BIO Temperate:Subtropical/Tropical 4 5
NA -0.09 0.16 -0.41 0.23
Odds Ratio 4
5 NA 0.91 NA 0.66 1.26
On 3 Oct 2010, at 15:29, Frank Harrell wrote:
You still seem to be hung up on making arbitrary classifications. Instead,
look at tendencies using odds ratios or rank correlation measures. My book
Regression Modeling Strategies covers this.
Frank
-----
Frank Harrell
Department of Biostatistics, Vanderbilt University
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