I am struggling with how to set up my regression robustness check. I am currently running a regression of recycling rates on income, population density and several other variables.
I have panel data of 350 local authorities over 20 quarters so have used
xtset acode qdate
xtreg recycling loginc logpopden loghhsize (unitary) md11 md12 md13 md14 md15 md16 md17 md18 md19 md20 md21 md22 md23 md24 md25 md26 md27 md28 md29 md291 wasteavg dryavg quarter2 quarter3 quarter4, fe vce(robust)
Some local authorities are Unitary and some are not. I would like to test whether unitary authorities have a higher recycling rate, however whenever I include my dummy for Unitary (takes the value one if that local authority is unitary), I get collinearity. Have I missed something?
Should I run two separate regressions for if Unitary= 1 and Unitary =0 and test if they are statistically different?
Below is a sample of my data.
Thank you!
Code:
* Example generated by -dataex-. To install: ssc install dataex clear input str43 name str9 code int year byte quarter float(qdate quarter2 quarter3 quarter4 recycling loginc logpopden loghhsize) byte unitarydummy "Hartlepool Borough Council" "E06000001" 2012 1 208 0 0 0 31.64322 9.576926 2.2529745 .8586616 1 "Hartlepool Borough Council" "E06000001" 2012 2 209 1 0 0 29.11372 9.576926 2.261659 .8586616 1 "Hartlepool Borough Council" "E06000001" 2012 3 210 0 1 0 24.318804 9.576926 2.261659 .8586616 1 "Hartlepool Borough Council" "E06000001" 2012 4 211 0 0 1 23.49204 9.576926 2.261659 .8586616 1 "Hartlepool Borough Council" "E06000001" 2013 1 212 0 0 0 29.75906 9.58011 2.2631164 .8628899 1 "Hartlepool Borough Council" "E06000001" 2013 2 213 1 0 0 25.608576 9.58011 2.2631164 .8628899 1 "Hartlepool Borough Council" "E06000001" 2013 3 214 0 1 0 19.14898 9.58011 2.2631164 .8628899 1 "Hartlepool Borough Council" "E06000001" 2013 4 215 0 0 1 26.363016 9.58011 2.2631164 .8628899 1 "Hartlepool Borough Council" "E06000001" 2014 1 216 0 0 0 29.21854 9.606159 2.2677865 .8671005 1 "Hartlepool Borough Council" "E06000001" 2014 2 217 1 0 0 22.891203 9.606159 2.2631164 .8671005 1 "Hartlepool Borough Council" "E06000001" 2014 3 218 0 1 0 22.664324 9.606159 2.2677865 .8671005 1 "Hartlepool Borough Council" "E06000001" 2014 4 219 0 0 1 19.374 9.606159 2.2677865 .8671005 1 "Hartlepool Borough Council" "E06000001" 2015 1 220 0 0 0 25.64599 9.642772 2.2669578 .8671005 1 "Hartlepool Borough Council" "E06000001" 2015 2 221 1 0 0 24.093536 9.642772 2.2669578 .8671005 1 "Hartlepool Borough Council" "E06000001" 2015 3 222 0 1 0 23.910435 9.642772 2.2669578 .8671005 1 "Hartlepool Borough Council" "E06000001" 2015 4 223 0 0 1 22.74303 9.642772 2.2669578 .8671005 1 "Hartlepool Borough Council" "E06000001" 2016 1 224 0 0 0 25.628105 9.620527 2.265921 .8712934 1 "Hartlepool Borough Council" "E06000001" 2016 2 225 1 0 0 21.490993 9.620527 2.265921 .8712934 1 "Hartlepool Borough Council" "E06000001" 2016 3 226 0 1 0 20.56008 9.620527 2.265921 .8712934 1 "Hartlepool Borough Council" "E06000001" 2016 4 227 0 0 1 19.26644 9.620527 2.265921 .8712934 1 "Middlesbrough Borough Council" "E06000002" 2012 1 208 0 0 0 15.01909 9.554639 3.262778 .8586616 1 "Middlesbrough Borough Council" "E06000002" 2012 2 209 1 0 0 14.171424 9.554639 3.234316 .8586616 1 "Middlesbrough Borough Council" "E06000002" 2012 3 210 0 1 0 13.453314 9.554639 3.234316 .8586616 1 "Middlesbrough Borough Council" "E06000002" 2012 4 211 0 0 1 13.24626 9.554639 3.234316 .8586616 1 "Middlesbrough Borough Council" "E06000002" 2013 1 212 0 0 0 14.57947 9.564863 3.236794 .8628899 1 "Middlesbrough Borough Council" "E06000002" 2013 2 213 1 0 0 14.828068 9.564863 3.236794 .8628899 1 "Middlesbrough Borough Council" "E06000002" 2013 3 214 0 1 0 14.709766 9.564863 3.236794 .8628899 1 "Middlesbrough Borough Council" "E06000002" 2013 4 215 0 0 1 20.44064 9.564863 3.236794 .8628899 1 "Middlesbrough Borough Council" "E06000002" 2014 1 216 0 0 0 34.159927 9.601301 3.2381685 .8671005 1 "Middlesbrough Borough Council" "E06000002" 2014 2 217 1 0 0 24.25953 9.601301 3.236794 .8671005 1 "Middlesbrough Borough Council" "E06000002" 2014 3 218 0 1 0 24.04574 9.601301 3.2381685 .8671005 1 "Middlesbrough Borough Council" "E06000002" 2014 4 219 0 0 1 24.127 9.601301 3.2381685 .8671005 1 "Middlesbrough Borough Council" "E06000002" 2015 1 220 0 0 0 27.94404 9.626811 3.239502 .8671005 1 "Middlesbrough Borough Council" "E06000002" 2015 2 221 1 0 0 23.334343 9.626811 3.239502 .8671005 1 "Middlesbrough Borough Council" "E06000002" 2015 3 222 0 1 0 19.43632 9.626811 3.239502 .8671005 1 "Middlesbrough Borough Council" "E06000002" 2015 4 223 0 0 1 23.32905 9.626811 3.239502 .8671005 1 "Middlesbrough Borough Council" "E06000002" 2016 1 224 0 0 0 23.50695 9.613669 3.24228 .8712934 1 "Middlesbrough Borough Council" "E06000002" 2016 2 225 1 0 0 20.070557 9.613669 3.24228 .8712934 1 "Middlesbrough Borough Council" "E06000002" 2016 3 226 0 1 0 19.601873 9.613669 3.24228 .8712934 1 "Middlesbrough Borough Council" "E06000002" 2016 4 227 0 0 1 21.82984 9.613669 3.24228 .8712934 1 "Redcar and Cleveland Borough Council" "E06000003" 2012 1 208 0 0 0 23.51096 9.537339 1.728642 .8586616 1 "Redcar and Cleveland Borough Council" "E06000003" 2012 2 209 1 0 0 20.10306 9.537339 1.712536 .8586616 1 "Redcar and Cleveland Borough Council" "E06000003" 2012 3 210 0 1 0 19.72007 9.537339 1.712536 .8586616 1 "Redcar and Cleveland Borough Council" "E06000003" 2012 4 211 0 0 1 22.403687 9.537339 1.712536 .8586616 1 "Redcar and Cleveland Borough Council" "E06000003" 2013 1 212 0 0 0 24.170063 9.545955 1.710911 .8628899 1 "Redcar and Cleveland Borough Council" "E06000003" 2013 2 213 1 0 0 23.99578 9.545955 1.710911 .8628899 1 "Redcar and Cleveland Borough Council" "E06000003" 2013 3 214 0 1 0 24.617693 9.545955 1.710911 .8628899 1 "Redcar and Cleveland Borough Council" "E06000003" 2013 4 215 0 0 1 30.60893 9.545955 1.710911 .8628899 1 "Redcar and Cleveland Borough Council" "E06000003" 2014 1 216 0 0 0 36.69286 9.575816 1.7105495 .8671005 1 "Redcar and Cleveland Borough Council" "E06000003" 2014 2 217 1 0 0 23.24818 9.575816 1.710911 .8671005 1 "Redcar and Cleveland Borough Council" "E06000003" 2014 3 218 0 1 0 28.21425 9.575816 1.7105495 .8671005 1 "Redcar and Cleveland Borough Council" "E06000003" 2014 4 219 0 0 1 33.378 9.575816 1.7105495 .8671005 1 "Redcar and Cleveland Borough Council" "E06000003" 2015 1 220 0 0 0 34.828026 9.600556 1.711272 .8671005 1 "Redcar and Cleveland Borough Council" "E06000003" 2015 2 221 1 0 0 26.965475 9.600556 1.711272 .8671005 1 "Redcar and Cleveland Borough Council" "E06000003" 2015 3 222 0 1 0 18.484371 9.600556 1.711272 .8671005 1 "Redcar and Cleveland Borough Council" "E06000003" 2015 4 223 0 0 1 22.8024 9.600556 1.711272 .8671005 1 "Redcar and Cleveland Borough Council" "E06000003" 2016 1 224 0 0 0 25.000637 9.583902 1.713077 .8712934 1 "Redcar and Cleveland Borough Council" "E06000003" 2016 2 225 1 0 0 23.34894 9.583902 1.713077 .8712934 1 "Redcar and Cleveland Borough Council" "E06000003" 2016 3 226 0 1 0 20.75586 9.583902 1.713077 .8712934 1 "Redcar and Cleveland Borough Council" "E06000003" 2016 4 227 0 0 1 25.922733 9.583902 1.713077 .8712934 1 "Stockton-on-Tees Borough Council" "E06000004" 2012 1 208 0 0 0 20.72435 9.607841 2.19778 .8586616 1 "Stockton-on-Tees Borough Council" "E06000004" 2012 2 209 1 0 0 19.85636 9.607841 2.1946657 .8586616 1 "Stockton-on-Tees Borough Council" "E06000004" 2012 3 210 0 1 0 17.278917 9.607841 2.1946657 .8586616 1 "Stockton-on-Tees Borough Council" "E06000004" 2012 4 211 0 0 1 20.15345 9.607841 2.1946657 .8586616 1 "Stockton-on-Tees Borough Council" "E06000004" 2013 1 212 0 0 0 22.03593 9.608176 2.197891 .8628899 1 "Stockton-on-Tees Borough Council" "E06000004" 2013 2 213 1 0 0 18.222332 9.608176 2.197891 .8628899 1 "Stockton-on-Tees Borough Council" "E06000004" 2013 3 214 0 1 0 17.56083 9.608176 2.197891 .8628899 1 "Stockton-on-Tees Borough Council" "E06000004" 2013 4 215 0 0 1 19.13032 9.608176 2.197891 .8628899 1 "Stockton-on-Tees Borough Council" "E06000004" 2014 1 216 0 0 0 21.184946 9.632138 2.201991 .8671005 1 "Stockton-on-Tees Borough Council" "E06000004" 2014 2 217 1 0 0 13.187984 9.632138 2.201991 .8671005 1 "Stockton-on-Tees Borough Council" "E06000004" 2014 3 218 0 1 0 16.005465 9.632138 2.201991 .8671005 1 "Stockton-on-Tees Borough Council" "E06000004" 2014 4 219 0 0 1 18.041 9.632138 2.201991 .8671005 1 "Stockton-on-Tees Borough Council" "E06000004" 2015 1 220 0 0 0 20.246767 9.662816 2.206735 .8671005 1 "Stockton-on-Tees Borough Council" "E06000004" 2015 2 221 1 0 0 16.660748 9.662816 2.206735 .8671005 1 "Stockton-on-Tees Borough Council" "E06000004" 2015 3 222 0 1 0 15.44666 9.662816 2.206735 .8671005 1 "Stockton-on-Tees Borough Council" "E06000004" 2015 4 223 0 0 1 18.055502 9.662816 2.206735 .8671005 1 "Stockton-on-Tees Borough Council" "E06000004" 2016 1 224 0 0 0 17.611841 9.641798 2.2102504 .8712934 1 "Stockton-on-Tees Borough Council" "E06000004" 2016 2 225 1 0 0 14.851618 9.641798 2.2102504 .8712934 1 "Stockton-on-Tees Borough Council" "E06000004" 2016 3 226 0 1 0 14.507548 9.641798 2.2102504 .8712934 1 "Stockton-on-Tees Borough Council" "E06000004" 2016 4 227 0 0 1 17.83563 9.641798 2.2102504 .8712934 1 "Darlington Borough Council" "E06000005" 2012 1 208 0 0 0 42.36351 9.570878 1.6325684 .8586616 1 "Darlington Borough Council" "E06000005" 2012 2 209 1 0 0 32.836056 9.570878 1.678964 .8586616 1 "Darlington Borough Council" "E06000005" 2012 3 210 0 1 0 31.34309 9.570878 1.678964 .8586616 1 "Darlington Borough Council" "E06000005" 2012 4 211 0 0 1 32.1052 9.570878 1.678964 .8586616 1 "Darlington Borough Council" "E06000005" 2013 1 212 0 0 0 28.556936 9.597573 1.6757873 .8628899 1 "Darlington Borough Council" "E06000005" 2013 2 213 1 0 0 30.584833 9.597573 1.6757873 .8628899 1 "Darlington Borough Council" "E06000005" 2013 3 214 0 1 0 28.63693 9.597573 1.6757873 .8628899 1 "Darlington Borough Council" "E06000005" 2013 4 215 0 0 1 21.55379 9.597573 1.6757873 .8628899 1 "Darlington Borough Council" "E06000005" 2014 1 216 0 0 0 20.11268 9.606159 1.6770965 .8671005 1 "Darlington Borough Council" "E06000005" 2014 2 217 1 0 0 26.908495 9.606159 1.6757873 .8671005 1 "Darlington Borough Council" "E06000005" 2014 3 218 0 1 0 25.60923 9.606159 1.6770965 .8671005 1 "Darlington Borough Council" "E06000005" 2014 4 219 0 0 1 30.62015 9.606159 1.6770965 .8671005 1 "Darlington Borough Council" "E06000005" 2015 1 220 0 0 0 31.480186 9.65098 1.6769096 .8671005 1 "Darlington Borough Council" "E06000005" 2015 2 221 1 0 0 29.34417 9.65098 1.6769096 .8671005 1 "Darlington Borough Council" "E06000005" 2015 3 222 0 1 0 29.5002 9.65098 1.6769096 .8671005 1 "Darlington Borough Council" "E06000005" 2015 4 223 0 0 1 25.388384 9.65098 1.6769096 .8671005 1 "Darlington Borough Council" "E06000005" 2016 1 224 0 0 0 29.34344 9.647757 1.6770965 .8712934 1 "Darlington Borough Council" "E06000005" 2016 2 225 1 0 0 27.49854 9.647757 1.6770965 .8712934 1 "Darlington Borough Council" "E06000005" 2016 3 226 0 1 0 28.14532 9.647757 1.6770965 .8712934 1 "Darlington Borough Council" "E06000005" 2016 4 227 0 0 1 28.00815 9.647757 1.6770965 .8712934 1 end format %tq qdate
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