coefficient that fluctuates over a wider range (from -0.108 to -0.042). These results hold even when we include the indicators of export product and export market concentration.

|**Table 4. Trade, diver**<br>_Dependent variable, Grow_<br>_Estimation Method: GMM_|**sification a**<br>_th of real GD_<br> _-IV System Es_<br>|**nd growth:**<br>_P per worker (5_<br>_timator (Arella_<br>|**Primary vs.**<br>_-year non-overl_<br>_no and Bover, 1_<br>|**Manufacturin**<br>_apping averages)_<br>_995; Blundell and_<br>|**g Exports.**<br> <br>_Bond,1998)_<br>||
|---|---|---|---|---|---|---|
||[1]|[2]|[3]|[4]|[5]|[6]|
|Initial GDP per worker|-0.0247<sup>***</sup>|-0.020<sup>***</sup>|-0.022<sup>***</sup>|-0.0213<sup>***</sup>|-0.018<sup>***</sup>|-0.018<sup>***</sup>|
|_(in logs)_|(0.000)|(0.000)|(0.000)|(0.000)|(0.000)|(0.000)|
|Total Exports (X)|0.0612<sup>***</sup>||||||
|<br>(M_anufacturing + primary)_|(0.000)||||||
|Exports, manufacturing||0.089<sup>***</sup>|0.098<sup>***</sup>||||
|_(% of GDP)_||(0.000)|(0.000)||||
|Exports, primary||-0.104<sup>***</sup>|-0.002||||
|_(% of GDP)_||(0.000)|(0.827)|00368<sup>***</sup>|||
|Total Trade (X+M)||||.<br>(0.000)|||
|<br>_(Manufacturing + primary)_|||||||
|Trade (X+M), manufacturing|||||0.062<sup>***</sup>|0.067<sup>***</sup>|
|_(% of GDP)_|||||(0.000)|(0.000)|
|Trade (X+M), primary|||||-0.108<sup>***</sup>|-0.042<sup>***</sup>|
|<br>_(% of GDP)_|||||(0.000)|(0.000)|
|Market Concentration|0.00881<sup>***</sup>||0.005<sup>**</sup>|0.0119<sup>***</sup>||0.006<sup>**</sup>|
|_(Herfindahl Index)_|(0.000)||(0.004)|(0.000)||(0.005)|
|Product Concentration|-0.0246<sup>***</sup>||-0.020<sup>***</sup>|-0.0277<sup>***</sup>||-0.020<sup>***</sup>|
|_(Herfindahl Index)_|(0.000)||(0.000)|(0.000)||(0.000)|
|Secondary enrollment rate|0.00951<sup>***</sup>|0.015<sup>***</sup>|0.009<sup>***</sup>|0.00822<sup>***</sup>|0.014<sup>***</sup>|0.008<sup>***</sup>|
|<br>_(initial level, logs)_|(0.000)|(0.000)|(0.000)|(0.000)|(0.000)|(0.000)|
|ICRG Political Risk Index|0.00475<sup>***</sup>|0.009<sup>***</sup>|0.004<sup>***</sup>|0.00381<sup>***</sup>|0.008<sup>***</sup>|0.003<sup>***</sup>|
|_(principal components)_|(0.000)|(0.000)|(0.000)|(0.000)|(0.000)|(0.000)|
|Credit to private sector|-0.0125<sup>***</sup>|-0.015<sup>***</sup>|-0.017<sup>***</sup>|-0.0148<sup>***</sup>|-0.015<sup>***</sup>|-0.019<sup>***</sup>|
|<br>_(% of GDP)_|(0.000)|(0.000)|(0.000)|(0.000)|(0.000)|(0.000)|
|Government consumption|0.00572<sup>***</sup>|0.006<sup>**</sup>|0.011<sup>***</sup>|0.00119|-0.001|0.005<sup>***</sup>|
|<br>_(% of GDP)_|(0.000)|(0.001)|(0.000)|(0.521)|(0.400)|(0.000)|
|Growth volatility|0.137<sup>***</sup>|0.227<sup>***</sup>|0.156<sup>***</sup>|0.201<sup>***</sup>|0.265<sup>***</sup>|0.221<sup>***</sup>|
|<br>_(S.D. growth per worker)_|(0.000)|(0.000)|(0.000)|(0.000)|(0.000)|(0.000)|
|Constant|0.195<sup>***</sup>|0.194<sup>***</sup>|0.181<sup>***</sup>|0.180<sup>***</sup>|0.191<sup>***</sup>|0.170<sup>***</sup>|
||(0.000)|(0.000)|(0.000)|(0.000)|(0.000)|(0.000)|
|Observations|595|614|595|589|607|589|
|<br>_AR(1)_|<br>0.002|<br>0.005|<br>0.003|<br>0.001|<br>0.003|<br>0.002|
|_AR(2)_|0.425|0.675|0.516|0.505|0.809|0.676|
|<br>_Hansen_|0.566|0.426|0.724|0.507|0.521|0.689|
|_p_-values in parentheses<br>|||||||
|* _p_ <0.05,** _p_ <0.01,*** _p_|<0.001||||||

Using our coefficient estimates in column [6] of Table 4, we find that reducing in half the ratio of exports and imports of primary goods (as a percentage to GDP) in Sub-Saharan Africa would lead to an increase in the annual rate of growth per worker of 0.5 percentage point. Another way to estimate the 17