I do not understand how to do question.

Opinion:Target should add an organic grocery selection to the stores. If they do ths, Target's organic clothing business will double in each of these stores.

Substantiation:"Wal-Mart believes so strongly in the synergy between healthy food and the rest of their business, they have decided that every new Wal-Mart store will be built to accommodate healthy grocery business.They measured customer traffic in existing Wal-Mart units before and after healthy grocery was added.They found that with the addition of healthy grocery, customer visits actually doubled."[WWD, 9-22-11, "An Interview with Top Management"]

Questions:

2a. Why isn't this substantiation convincing?

2b. What type of information would be convincing?