Hi i was wondering if anyone could help me
I am running the following tobit regression:

Code:
 tobit expshare_wine_on l_p_wine_on l_p_beer_on l_p_spirits_on l_p_cider_on l_p_alcopops_on l_p_wine_off l_p_beer_off l_p_spirits_off l_p_cider_off l_p_alcopops_off logincome _Isexhrp_2 _Iyear_2008 _Iyear_2009 _Iyear_2010 _Iyear_2011 _Iyear_2012 _Isocio_gro_2 _Isocio_gro_3 _Isocio_gro_4 _Isocio_gro_5 _Isocio_gro_6 _Igor_2 _Igor_3 _Igor_4 _Igor_5 _Igor_6 _Igor_7, ll(0)
where the dependent Variable is the expenditure share of wine and the other independent variables include the logs of prices: wine, spirits, cider, alcopops and beer on and off trade. Other explanatory variables are log income, years (with 2007 omitted) , socio-economic groups (with group 1 omitted), gender( with males omitted) and government region (with group 1 omitted)

when i run the regression i am able to get results for all variables except from : all the years and half the log price variables (the on trade prices give results but the off trade ones do not) and it displays:

Code:
 note: l_p_wine_off omitted because of collinearity
note: l_p_beer_off omitted because of collinearity
note: l_p_spirits_off omitted because of collinearity
note: l_p_cider_off omitted because of collinearity
note: l_p_alcopops_off omitted because of collinearity
note: 2008.year omitted because of collinearity
note: 2009.year omitted because of collinearity
note: 2010.year omitted because of collinearity
note: 2011.year omitted because of collinearity
note: 2012.year omitted because of collinearity
 and
I don't know why this is or how to solve it so would really appreciate any help
Thanks so much
Anya