odds ratio

[George. J. Pappas]

Hello every one I am trying to calculate the odds ratio with the spss.
Should I use descriptive statistics-crosstabs-risk or binary logistic
regression and Exp(B). Isn't Exp(B) the same as odds ratio? I thank you all
in advance.

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[Norberto Hernandez]

George, you are (virtually) correct. The crosstabs procedure will give you the Undajusted OR (you are only measuring the effect of IV in DV) but in the logistic regressión you can obtain the Adjusted OR (and allows you to study the effects of IV in presence of other variables which may have effect in the DV). Try to make a logistic regression with DV and IV and the output is exactly the same as crosstabs.

Greetings!

Norberto

2014-02-13 10:43 GMT-06:00 George. J. Pappas <[hidden email]>:

Hello every one I am trying to calculate the odds ratio with the spss.
Should I use descriptive statistics-crosstabs-risk or binary logistic
regression and Exp(B). Isn't Exp(B) the same as odds ratio? I thank you all
in advance.

=====================
To manage your subscription to SPSSX-L, send a message to
[hidden email] (not to SPSSX-L), with no body text except the
command. To leave the list, send the command
SIGNOFF SPSSX-L
For a list of commands to manage subscriptions, send the command
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[PRogman]

When computing odds ratio (OR) using then Risk option in Crosstabs SPSS always sorts the variable values in ascending order.  If your variables are coded 0|1 you get the OR of the 0 value, it is the same OR as it is symmetric:
OR defined as = ad/bc

         1      |    0
      -----------------
  1 |  11 (a) |  10 (b)
  0 |  01 (c) |  00 (d)

and SPSS sorts this to

       0  |   1
      ---------
  0 |  00 |  01
  1 |  10 |  11

and still calculates OR as the first table...
Use binary linlog to get the results you want including confidence intervals, especially if you are coding variables 0|1.
(or use 0=yes and 1=no ?????)

I wish there was an option in Crosstabs (like in LogReg) to specify the reference category.

/PR

[Bruce Weaver]

If you want CROSSTABS to give the same OR as LOGISTIC REGRESSION, use a temporary RECODE, as in the example shown here:

http://spssx-discussion.1045642.n5.nabble.com/compute-logit-and-compare-regression-coef-linear-and-logistic-tp5724493p5724496.html

PRogman wrote

When computing odds ratio (OR) using then Risk option in Crosstabs SPSS always sorts the variable values in ascending order.  If your variables are coded 0|1 you get the OR of the 0 value, it is the same OR as it is symmetric:
OR defined as = ad/bc

         1      |    0
      -----------------
  1 |  11 (a) |  10 (b)
  0 |  01 (c) |  00 (d)

and SPSS sorts this to

       0  |   1
      ---------
  0 |  00 |  01
  1 |  10 |  11

and still calculates OR as the first table...
Use binary linlog to get the results you want including confidence intervals, especially if you are coding variables 0|1.
(or use 0=yes and 1=no ?????)

I wish there was an option in Crosstabs (like in LogReg) to specify the reference category.

/PR