Dear list,
>I have a question about the selection of Variables in dataframes.
>I have a dataframes like this:
>
>CFISCA FIRMS YEAR VAR VALUE
>20345 nike 2005 EC01 34
>20345 nike 2006 EC01 45
>56779 mediaset 2005 EC01 65
>64568 agazzini 2005 EC01 78
>64568 agazzini 2006 EC01 56
>78907 uniteam 2006 EC01 46
>
>
>what my result should be is a new dataframes which have only firms which have
>data in both years (2005,2006)
>
>CFISCA FIRMS YEAR VAR VALUE
>20345 nike 2005 EC01 34
>20345 nike 2006 EC01 45
>64568 agazzini 2005 EC01 78
>64568 agazzini 2006 EC01 56
>
>
>Thanks for your attention!!!
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