$2.$ Opinion: Target should add a full grocery selection to the stores that remain without it$.$ If they do this, Target$$s apparel business will double in each of these stores.

Substantiation: $$Wal$-$Mart believes so strongly in the synergy between grocery and the rest of their business, they have decided that every new Wal$-$Mart store will be built to accommodate grocery. They measured customer traffic in existing Wal$-$Mart units before and after grocery was added. They found that with the addition of grocery, customer visits actually doubled.$[$WWD$,$An Interview with Top Management$]$

Questions:

$2$a$.$ Why isn$$t this substantiation convincing?

$2$b$.$ What type of information would be convincing?