Final answer:
The buyer at J. Crew is using historical sales data to plan orders for the next summer. This historical data helps predict future sales but may have limitations such as assuming consistent customer flow or individual shopping behaviors.
Step-by-step explanation:
The data source that the buyer at J. Crew is using to plan orders for next summer would be considered historical sales data.
This is information that the retailer has collected from past sales performances during the same time period, which is an example of internal data. Planning inventory based on past sales trends can help to predict future sales, but may contain limitations such as customer count irregularities and changing shopping patterns not being factored into the predictive model.
For example, the model might assume a consistent flow of customers throughout the day or that customers shop individually rather than in groups, which may not always be accurate. Therefore, while historical sales data is valuable, it's important to be mindful of its potential restrictions.