reg commute volunteer , robust Linear regression Number of obs 994 F ( 1 , 992 ) 11 . 46 Prob gt; F 0. 0007 R - squared = 0 . 01 14 Root MISE 56 ....

Hello Tutors.

Can someone please help me with this question:

What do the results say about the internal validity and external validity of the experiment? ( see picture)

Thank you :D

reg commute volunteer , robustLinear regressionNumber of obs994F ( 1 , 992 )11 . 46Prob > F0. 0007R - squared=0 . 01 14Root MISE56 . 136RobustcommuteCoef .Sta . Err .tP > It ![ 95% Conf . Interval]volunteer12 . 031843. 5543153. 390 . 0015 . 05699619 . 00667- cons74 . 465582 . 31603732 . 150 . 00069 . 9206979 . 01048The coefficient 12 . 03 indicates that those who volunteered for the experiment have 12minutes longer commute time than those who did not volunteer for the experiment .This estimate is statistically significant at the 1% level .reg tenure volunteer , robustLinear regressionNumber of obs994F ( 1 , 992 )7 . 45Prob > F0 . 0065R - squared0 . 0075Root MSE=20 . 909Robusttenure |Coet .Sta . Err .P > It ![ 95% Conf . Interval]- - - -volunteerI- 3 . 62347 11 . 327417- 2. 730 . 006- 6 . 228338- 1 . 018604cons26 . 8421697 170461000 ' 027 . 6224 . 9353328. 74899The coefficient - 3. 62 indicates that the average tenure of those who volunteered for theexperiment is 3. 62 years lower than those who did not volunteer for the experiment .This estimate is also statistically significant at the 1 % level .