Testing equality of two coefficients

[Fathima Salih]

I run the following regression

reg y x1 x2

If I want to test whether the coefficients are equal I use

test x1=x2

Can someone please help me with how I test if the interacted coefficients are equal if I interact x1 and x2 with variable drought? drought=1 if the household suffered from drought and 0 otherwise.

reg y c.x1##i.drought c.x2##i.dought

[Andrew Musau]

Consider:

sysuse auto, clear
reg price c.mpg##i.rep78 c.weight##i.rep78
forval i=2/5{
    test `i'.rep78#c.mpg=`i'.rep78#c.weight
}

Res.:

. forval i=2/5{
  2.
.     test `i'.rep78#c.mpg=`i'.rep78#c.weight
  3.
. }

 ( 1)  2.rep78#c.mpg - 2.rep78#c.weight = 0

       F(  1,    55) =    2.02
            Prob > F =    0.1604

 ( 1)  3.rep78#c.mpg - 3.rep78#c.weight = 0

       F(  1,    55) =    1.23
            Prob > F =    0.2727

 ( 1)  4.rep78#c.mpg - 4.rep78#c.weight = 0

       F(  1,    55) =    0.76
            Prob > F =    0.3863

 ( 1)  5.rep78#c.mpg - 5o.rep78#co.weight = 0

       F(  1,    55) =    1.32
            Prob > F =    0.2554

.

I am sure that test has some syntax to directly do this, but it is not immediately apparent to me. Note that for a binary variable, there is only 1 test, so

test 1.drought#c.x1 = 1.drought#c.x2