Portuguese ( _Treated_ 4). However, for matched samples [Columns (2) and (3)], the first coefficient becomes statistically non-significant and the coefficient of _Treated_ 3 related to Higher Education in Portuguese becomes statistically significant at 10% of significance.

Thus, the initial results indicate that the only change in teachers’ education indicators capable of affecting students’ scores was that related to the increase in Percentage of Portuguese Classes Taught by Teachers with Higher Education in Portuguese, especially among the schools that had the highest increases ( _Treaded_ 4). For these schools, whose indicator was below 43% [or 20.1%, on average] in the year 2009 and has risen above 94% [or 99.9%, on average] in the year 2015, the estimated _ATT_ is between 6.9 and 7.5 points in Portuguese exam, what implies in an mean increase between 0.086 and 0.094 points for every 1 percentage point increase in teachers education indicator. This estimated effect is about 3 times the one previously estimated in the regressions without characterizing the treatment from binary variables, which considers all schools [see Table 11, Columns (2) and (3)].

Table 11 – Estimates of Treatment Effects on Mathematics and Portuguese Scores

||||All schools<br>||Participati<br>|on restriction<br>|on schools<br>|
|---|---|---|---|---|---|---|---|
|Teachers<br>education|Treatment<br>group|No<br>matching<br>(1)|Radius<br>matching<br>(2)|Kernel<br>matching<br>(3)|No<br>matching<br>(4)|Radius<br>matching<br>(5)|Kernel<br>matching<br>(6)|
||||_Math sc_<br>|_ores_<br>||||
||Treated1|1.496|2.386|2.454|-1.082|-0.568|-0.620|
|Hih|Treated 2|1.116|1.684|1.672|1.215|0.057|0.684|
|ger<br>education|Treated 3|0.731|0.838|1.692|3.716|4.148|5.185*|
||Treated 2,3|0.368|1.146|1.395|3.653*|4.533**|4.191*|
||Treated 1,2,3|0.602|0.970|1.141|1.780|2.371|2.336|
||Treated 1|0.033|-0.442|-0.349|-0.352|-0.217|-0.251|
|Hih|Treated 2|-0.048|0.289|0.390|-0.283|0.101|0.236|
|ger<br>education in|Treated 3|0.277|-0.177|-0.106|-2.688|-1.682|-1.285|
|<br>Math|Treated 4|-0.302|1.398|1.375|2.065|2.658|3.088|
||Treated 2,3,4|-0.471|0.710|0.640|0.0639|0.426|0.146|
||Treated 1,2,3,4|0.0670|0.628|0.614|0.648|0.886|0.793|
||||_Portugues_<br>|_e scores_<br>||||
||Treated 1|0.808|-0.403|-0.385|1.358|1.005|0.932|
|Hih|Treated 2|1.633|0.359|0.385|1.725|1.652|1.666|
|ger<br>education|Treated 3|5.017**|2.066|2.114|4.365|4.044|4.185|
||Treated 2,3|2.533|0.707|0.672|1.391|1.099|0.967|
||Treated 1,2,3|1.831|0.307|0.545|2.321|1.324|1.212|
||Treated 1|2.909|2.972|2.357|1.917|1.651|1.745|
||Treated 2|-1.189|-0.882|-1.433|0.211|-0.601|-0.836|
|Higher<br>datin in|Treated 3|3.544|4.543*|4.367*|2.483|2.335|1.805|
|euco<br>Portuguese|Treated 4|7.598***|7.529***|6.908**|7.221**|3.980|4.275|
||Treated 2,3,4|1.778|2.643|2.595|2.302|1.189|1.442|
||Treated 1,2,3,4|1.724|2.736*|2.506|2.583|1.947|2.047|

_Note._ School level Fixed Effects Model with linear trends by UF (omitted). Covariates were omitted. Cluster-robust standard errors in parentheses. *Statistically significant at 10% significance level. **Statistically significant at 5% significance level. ***Statistically significant at 1% significance level.

Again, in order to verify the robustness of the results in relation to the presence in the sample of schools with low student participation rates in ENEM, we re-estimate the model for the restricted sample, which excludes schools whose participation rate in 2009 was below the median of the distribution. As we can see, the estimated coefficients for the non-matched sample are all statistically non-significant, with the exception of the coefficients for _Treated_ 2,3 related to the effect of the increase in the Teachers Higher Education on math scores and for _Treated_ 4 related to the effect of the increase in the Teachers Higher Education in Portuguese on Portuguese scores.

In regressions on paired samples [Columns (5) and (6)], however, the only coefficients that remains statistically significant are those for _Treated_ 2,3 related to the effect of the increase in the Teachers Higher Education on math scores, and the coefficient of _Treated_ 3 related to the effect of the increase in the Teacher Higher Education on math scores becomes statistically significant at 10% significance for the sample 16