Dear Statalist Users,

I have the following data. This dataset is at city level.

Plate=unique identifier of each province There are 81 provinces in this dataset.
Child Birth Year= It spans from 2003 to 2018. Indeed, they are just years.
Refugee Ratio= It is the number of refugees in each province divided by its own population. It takes 0 from 2003 to 2012 due to absence of refugees. Then, after 2013, it starts taking its values.
Region 5= It is region dummies. 1 includes provinces in North, 2 includes provinces in South, 3 includes provinces in West, 4 provinces cities in East, and 5 provinces cities in Central.
Instrument= It is an IV.
Log GDP Interpolated= GDP per capita at province level (only year 2003 is interpolated).

For example, when I try to look at the effect of refugees on GDP, I run the following codes to replicate the study I attached here:

(1) To include province and year FEs, I think it's okay. I replicate the author's Column (4) here.

ivreg2 log_gdp_interpolated ( refugeeratio =instrument_) i.plate i.child_birth_year, cluster(plate)

(2) To include province FE, year FE, and 5 Region Linear Time Trends, the regression says "Dropped collinear: 2.region5 3.region5 4.region5 5.region5. Here is the code I use.

ivreg2 log_gdp_interpolated ( refugeeratio =instrument_) i.plate i.child_birth_year i.region5, cluster(plate)

As you can see, I have just include region5 dummies. I also tried it without "i." and it was dropped again. So my question, how can I include the "5 Region Linear Time Trends" as the authors add as in their Column (5).

(3) Similarly, is this correct to replicate their Column (6) using the following code?

ivreg2 log_gdp_interpolated ( refugeeratio =instrument_) i.plate i.child_birth_year i.region5#i.child_birth_year, cluster(plate)

Thank you very much in advanced.

Array


Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input byte plate int child_birth_year float(region5 refugeeratio) double instrument_ float log_gdp_interpolated
1 2003 2            0                  0  8.098686
1 2004 2            0                  0   8.35625
1 2005 2            0                  0  8.560877
1 2006 2            0                  0 8.6270895
1 2007 2            0                  0  8.833439
1 2008 2            0                  0  8.950308
1 2009 2            0                  0  8.775798
1 2010 2            0                  0  8.951138
1 2011 2            0                  0   8.99517
1 2012 2            0                  0  9.039643
1 2013 2    .00899705  2137.502174204115  9.113099
1 2014 2   .028272137  7725.103785707176  9.062313
1 2015 2    .06261454  9552.797764008226  8.977292
1 2016 2     .0680111 10815.378820879647  8.983587
1 2017 2    .07022186  11869.59208789388  8.932284
1 2018 2    .08672575  13611.10083198924   8.81266
2 2003 5            0                  0   7.53345
2 2004 5            0                  0  7.804962
2 2005 5            0                  0  8.018276
2 2006 5            0                  0  8.095382
2 2007 5            0                  0  8.301027
2 2008 5            0                  0 8.4515085
2 2009 5            0                  0   8.24615
2 2010 5            0                  0  8.475749
2 2011 5            0                  0  8.558379
2 2012 5            0                  0  8.554743
2 2013 5   .017068442 1873.8649676118544   8.62631
2 2014 5    .05579131  6772.297838991608   8.59959
2 2015 5   .036632303  8374.566018545016   8.50638
2 2016 5    .04061859  9481.421693263867  8.488602
2 2017 5    .04283048 10405.609435989865  8.441897
2 2018 5    .04727203 11932.322374920604  8.375801
3 2003 3            0                  0  8.039925
3 2004 3            0                  0  8.265195
3 2005 3            0                  0  8.448931
3 2006 3            0                  0   8.52808
3 2007 3            0                  0  8.732327
3 2008 3            0                  0  8.862084
3 2009 3            0                  0  8.706999
3 2010 3            0                  0  8.930561
3 2011 3            0                  0  8.954763
3 2012 3            0                  0  8.963824
3 2013 3            0  775.6147412650209  9.015151
3 2014 3  .0007078433  2803.133697970472   9.02242
3 2015 3  .0040069674  3466.331335474366  8.934076
3 2016 3   .005851456  3924.471912625391  8.944426
3 2017 3   .006891223  4307.004085084045   8.93551
3 2018 3   .008190825  4938.928520185606  8.804566
4 2003 5            0                  0   7.34143
4 2004 5            0                  0  7.580326
4 2005 5            0                  0  7.773012
4 2006 5            0                  0  7.768281
4 2007 5            0                  0  7.943454
4 2008 5            0                  0  8.026946
4 2009 5            0                  0  7.925411
4 2010 5            0                  0  8.236918
4 2011 5            0                  0  8.225596
4 2012 5            0                  0  8.267767
4 2013 5            0  801.6362469490603  8.292835
4 2014 5 .00018200515   2897.17750035604 8.2031765
4 2015 5  .0014546518  3582.625103178801  8.123725
4 2016 5  .0015804373 4056.1360787997937  8.203612
4 2017 5  .0018795975   4451.50202371064  8.111795
4 2018 5  .0021050407  5104.627223064127  8.006121
5 2003 3            0                  0  8.037372
5 2004 3            0                  0  8.316185
5 2005 3            0                  0  8.533969
5 2006 3            0                  0  8.565304
5 2007 3            0                  0  8.739339
5 2008 3            0                  0   8.95324
5 2009 3            0                  0  8.813373
5 2010 3            0                  0  8.976414
5 2011 3            0                  0  9.006424
5 2012 3            0                  0  9.049225
5 2013 3            0  892.4989384510496  9.091903
5 2014 3  .0003106429  3225.562533397196  9.035556
5 2015 3  .0004469732  3988.703247419831  8.994672
5 2016 3  .0006649282  4515.885051754473 8.9999695
5 2017 3  .0012185954  4956.064356863975   8.93685
5 2018 3   .001688849   5683.21903495784  8.793315
6 2003 3            0                  0  8.820829
6 2004 3            0                  0  9.080735
6 2005 3            0                  0  9.286835
6 2006 3            0                  0  9.369869
6 2007 3            0                  0  9.585378
6 2008 3            0                  0  9.712936
6 2009 3            0                  0  9.521501
6 2010 3            0                  0  9.652315
6 2011 3            0                  0  9.694221
6 2012 3            0                  0  9.711046
6 2013 3            0  845.9475972730434  9.818029
6 2014 3   .005825161 3057.3222638415114  9.750788
6 2015 3    .01024025   3780.65875825695  9.638588
6 2016 3   .012557893  4280.343588669125  9.655186
6 2017 3   .014737303 4697.5638334046025  9.586901
6 2018 3   .017472614 5386.7912669373945  9.465929
7 2003 2            0                  0  8.747828
7 2004 2            0                  0  8.968632
7 2005 2            0                  0  9.149391
7 2006 2            0                  0  9.225716
end