Several factors converged last month—An earlier Easter holiday, better weather and improving spending plans by shoppers—to propel retail same-store sales excluding Walmart to a 9.2% gain in March, according to Kantar Retail. The sales-weighted composite for the 32 retailers reporting–most of them apparel retailers–was better than the 3.9% same-store sales gain last month and the 4.7% decline in March of 2009 for the same measure.Including Walmart, same-store sales were down 1.9% i...