1model,estimate,se,ci_low,ci_high2"unadjusted OLS (growth ~ hours), HC1",-0.13169790632300882,0.014619618827634278,-0.1603518326928757,-0.103043979953141953"adjusted OLS (growth ~ hours + skill_index), HC1 [main]",0.25353820594501253,0.009812212326345536,0.2343066231767153,0.272769788713309764"sensitivity: adjusted OLS incl. 12 negative-hours rows, HC1",0.25222449623309495,0.00947885217664965,0.23364628735208254,0.270802705114107375"sensitivity: adjusted OLS + skill_index^2, HC1",0.25383792381516485,0.009844473118691516,0.23454311105575676,0.273132736574572936