Dear Statlist users,

I am studying the impact of parental investments in early childhood, as recorded in the 1993 data set on adult labour market earnings(as observed in 2005). While the data set is household level panel data, what I am using is cross section as the investments in 1993 are not observed in 2005, just the impact on income in 2005. I have used areg to do a siblings fixed effects analysis, however I am struggling with doing an IV with sibling fixed effects. I wish to use the command xi: ivreg2 depvar (endogenous var=instrument) i.var, however this I understand i.var can be used only for categorical variables. My data is a survey data that contains mother's id that takes the value 1-28 and would take the same value for siblings. STATA therefore gives me a result like this for each of the 28 values:

parentaliindex | -3225.741 542.0528 -5.95 0.000 -4288.145 -2163.337
_Imothersid_1 | -7207.049 4750.07 -1.52 0.129 -16517.02 2102.917
_Imothersid_2 | -1449.11 3207.187 -0.45 0.651 -7735.082 4836.862
_Imothersid_3 | 14257.66 3713.269 3.84 0.000 6979.788 21535.53
_Imothersid_4 | 19519.84 3493.853 5.59 0.000 12672.01 26367.67
_Imothersid_5 | 33893.13 4362.288 7.77 0.000 25343.2 42443.06
_Imothersid_6 | 37477.25 4546.112 8.24 0.000 28567.04 46387.47
_Imothersid_7 | 29743.94 4651.685 6.39 0.000 20626.8 38861.07
_Imothersid_8 | 34198.41 4574.421 7.48 0.000 25232.71 43164.11

Is there a way I can do an IV for cross section data whilst including siblings/family fixed effects?

Regards,
Akanksha