Backward-looking studies, undermined by data mining, are a trap for investors, writes Gary Smith. : It is easy to identify successful companies, but hard to pin down the characteristics that make them successful. Why do some companies grow and prosper while others languish and fail? Why are some companies great while others are merely good, mediocre, or bad? These questions are asked and answered over and over again by business executives, management consultants, financial analysts, and investors, but their answers are usually wrong.