We longitudinally examine outcomes of entrepreneurial business planning to assess effectiveness. Both data replication and extension are used to examine previously published research. Our sample consists of 623 nascent ventures that we follow for more than ten years - from 1998 to 2010. Our findings highlight the importance of data replication, data extension, and sample selection bias. We not only add to the debate regarding the merits or liabilities of planning, but also contribute to evaluating normative research and publication standards by reexamining past research using more comprehensive data and an extended time frame.