separately  for  the  high  and  low  comparative  advantage  sectors,  although  the  interaction term  is  more  than  three  times  higher  in  magnitude  for  the  high  comparative  advantage sector.  These  results  continue  to  hold  when  we  use  effective  rate  of  protection  in  the  sector as  our  measure  of  trade  protection.

In  Table  4.2  we  present  a  wide  array  of  robustness  checks  we  have  conducted.  The  first  two columns  report  estimation  results  from  specification  (3)  for  various  alternative  samples.  In column  1,  we  use  a  5%  random  sample  of  males  in  metropolitan  areas  instead  of  a  1% random  sample  of  the  full  population.  In  column  2  we  restrict  our  analysis  to  only  the liberalization  period  (1990-­‐1994)  during  which  average  ERP  was  decreasing.  Our  results are  robust  to  these  alternative  samples  and  to  using  an  industry-­‐specific  real  exchange  rate measure  as  in  column  3,  instead  of  an  economy-­‐wide  measure.  Next,  we  test  whether  our result  of  insignificant  interaction  coefficient  is  sensitive  to  the  exporting  thresholds  we  use to  assign  the  indicator  variable  denoting  a  firm’s  export  status.  In  the  baseline  specifications a  firm  is  defined  as  an  exporter  if  it  exported  a  positive  dollar  amount  that  year.  Instead,  in columns  5  and  6,  we  only  consider  firms  with  an  export  value  more  than  the  5th  percentile (cutoff  5),  and  more  than  the  10th  percentile  (cutoff  10)  as  exporting  firms,  respectively. While  the  magnitude  of  the  interaction  term  increases  slightly  as  we  increase  the  cut  off threshold,  the  coefficient  remains  statistically  insignificantly  different  than  zero.  In  the  next two  columns  we  consider  two  time-­‐invariant  measures  of  export  status.  In  column  7,  a  firm is  defined  as  an  exporter  if  it  exported  a  positive  dollar  value  at  the  beginning  of  our  sample at  1990  (Export90).  The  export  status  variable  in  column  8  takes  the  value  1  if  the  firm reported  positive  exports  during  every  year  between  90  and  98.  Finally,  when  we  use  the magnitude  of  exports  for  the  sub-­‐sample  of  exporting  firms  to  represent  the  relevance  of exports  to  the  firm  instead,  we  obtain  yet  again  estimates  of !!" and !!" that  are insignificantly  different  from  zero.<sup>37</sup> Our  findings  using  worker  level  data  and  taking  endogenous  worker  mobility  into  account, suggests  an  insignificant  differential  effect  of  trade  policy  on  the  wages  of  workers

> 37   Other   robustness   checks   we   have   conducted   but   we   do   not   reported   to   conserve   space   include defining   a   firm   as   exporter   if   the   firm   exported   only   to   non-­‐Mercosur   countries   (and   omitting exporters   to   Mercosur   countries   from   the   sample)   and   using   a   more   detailed   industry   classification available   only   for   the   1994-­‐1998   period,   which   allows   us   to   identify   changes   in   industry   level   ERP   at a   more   disaggregated   level.   We   find   our   main   conclusions   to   be   robust.

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