Hi everybody!

For my masterthesis I need to do a data-analysis. I have a data set with the S&P 1500 companies and there unique CIK codes(they are the same for a company over the years) for the year 2006-2016. Now I want to delete all the observations in the dataset that haven't experienced an environmental controversie(0/1). So I want all the data of companies that expercienced an environmental controversie between 2006-2016. Only the companies that didn't experienced an environmental controversie must be dropped. For example if a company had a controversie in 2007 I want all the data of that company for 2006-2016 but if it hadn't a controversie between 2006-2016 the variable needs to be dropped.The difficulty is that over that time period the CIK code is the same so for a 2006 ,2007,..., 2016 the CIK code for the same company is the same

can somebody help me please ?

Thanks!