Dear Statalist users,
This is my first post here and sorry in advance if the post does not fully comply with the advices on posting.

I run the following regression:
ivreg2 lfood self_employed_1 self_employed_1#i.year log_income_diff age agesq lnhh housesq i.year (lperm = private_car sex)

I have the following regression output:
lfood Coef. Std. Err. z P>z [95% Conf. Interval]
lperm .2890392 .0059375 48.68 0.000 .2774019 .3006766
self_employed_1 .03577 .0073481 4.87 0.000 .021368 .0501719
self_employed_1#rok
1 2005 .0082357 .010991 0.75 0.454 -.0133062 .0297776
1 2006 .0190306 .0107994 1.76 0.078 -.0021358 .040197
1 2007 .007384 .0106777 0.69 0.489 -.0135438 .0283119
1 2008 .0069638 .010619 0.66 0.512 -.013849 .0277767
1 2009 .0049704 .0105409 0.47 0.637 -.0156893 .0256301
1 2010 .0025309 .0101807 0.25 0.804 -.0174229 .0224848
1 2011 -.0074874 .0102216 -0.73 0.464 -.0275215 .0125466
1 2012 .0129113 .0102845 1.26 0.209 -.0072459 .0330685
1 2013 .0061358 .010411 0.59 0.556 -.0142694 .0265411
1 2014 .0287141 .0104055 2.76 0.006 .0083198 .0491084
1 2015 .0187668 .0104033 1.80 0.071 -.0016233 .039157
1 2016 -.0033278 .0102994 -0.32 0.747 -.0235142 .0168587
1 2017 0 (omitted)
The interaction coefficients for self_employed_1*i.year are not statistically significant 2005, 2007-2013, and 2016. So, effect of self_employed_1 on lfood is same in these yars and the base year (2017).
However, when I use lincom, the joint coefficients of these interaction terms with self_employed_1 is statistically significant at 1% level. For example for year 2005, I have:
( 1) self_employed_1 + 1.self_employed_1#2005b.rok = 0
lfood Coef. Std. Err. z P>z [95% Conf. Interval]
(1) .0440057 .0082907 5.31 0.000 .0277561 .0602552
My question is the following:
How should I interpret these results? Should I interpret there is no change of under-reporting in year 2005 relative to the baseline year 2017 because the interaction coefficient is not significant and impact of self_employment_1 on lfood in year 2005 is .03577?
Or should I look at the results from lincom and say the impact of self_employment_1 on lfood in year 2005 is .0440057?

I am little confused and your help would be greatly appreciated.
Thank you.