Dear Michael,
If you want to know what happens when you change both age and democracy
from their min to their max values, you need to calculate the interaction
"by hand" and then include the calculation in simqi. Here's an example
summarize age1, meanonly /* get min and max of age1 */
local minage1 = `r(min)'
local maxage1 = `r(max)'
summarize dem1, meanonly /* get min and max of age2 */
local mindem1 = `r(min)'
local maxdem1 = `r(max)'
local minad = `minage1' * `mindem1' /* min of age1 x min of dem1 */
local maxad = `maxage1' * `maxdem1' /* max of age1 x max of dem1 */
simqi, fd(pr) changex(age1 min max dem1 min max AgeDem1 `minad' `maxad')
Good luck with your research, and thanks for your interest in Clarify.
Regards,
Michael Tomz
Assistant Professor, Stanford University
Department of Political Science
Encina Hall West, Stanford, CA 94305-6044
phone 650-725-4031 | fax 650-723-1808
On Mon, 17 May 2004, Michael Horowitz wrote:
I have a question about interaction terms and clarify
that I am not sure
about based on my reading of the archive.
I am using Clarify to get first differences and relative risks. For the
purpose of this example, I have 3 variables of interest. Age, Democracy,
and Age*Democracy.
When I use "setx" to get the mean of the variables, I set things up the
way it is recommended in the Clarify manual for interaction terms.
summarize age1, meanonly /* Compute the mean of x1 */
local mage1=`r(mean)' /* Save the mean in a local macro */
summarize dem1, meanonly /* Compute the mean of x2 */
local mdem1=`r(mean)' /* Save the mean in a local macro */
setx AgeDem1 `mage1'*`mdem1' /* Setx to mean(x1)*mean(x2) */
summarize age2, meanonly /* Compute the mean of x1 */
local mage2=`r(mean)' /* Save the mean in a local macro */
summarize dem2, meanonly /* Compute the mean of x2 */
local mdem2=`r(mean)' /* Save the mean in a local macro */
setx AgeDem1 `mage2'*`mdem2' /* Setx to mean(x1)*mean(x2) */
But I am having trouble figuring out what to do when I subsequently
generate first differences. Do I need to do:
simqi, fd(pr) changex(AgeDem1 min max dem1 min max age1 min max)
OR can I just do
simqi, fd(pr) changex(AgeDem1 min max)
Any guidance you could provide would be much appreciated.
Michael Horowitz
*******************************************************************************
Michael Horowitz
78 Kirkland Street, #1
Cambridge, MA 02138
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