FACTBOX-Sizing up retailers' performance as online sales surge

As online shopping upends the retail business, many Wall Street analysts say traditional measures such as counting the number of people who visit stores on major shopping days are no longer a reliable gauge of a company's performance. Below are some of the newer methods that retail analysts are employing on the job, as well as some traditional ones.

NEWER TACTICS * Subscribing to retailers' emails to closely monitor promotions, flash sales, and doorbuster deals

* Counting the number of Instagram-led fashion brands in retailers' stores and online * Examining e-receipt data provided by consumers, recording when a customer was at a store and what they bought.

* Forming partnerships with third-party data analytics firms measuring things such as website visits and social media sentiment for a more holistic view * Counting the number of "off-price" stores in a retailer's fleet

* Counting the proportion or number of millennials and Gen Z customers shopping at the store TRADITIONAL MEASURES

* Same-store sales * Sales per square foot of retail space

* Counting cars at malls and in retailers' lots * Foot traffic

* Average selling price, calculated by dividing net sales by the number of products sold * Average basket size, or the average number of items sold in a single purchase, calculated by dividing the total number of units sold by the number of invoices

* Transaction velocity, or the rate at which transactions occur at a store or online * Conversion, or the proportion of people who visit a store or browse a website and ultimately purchase a product. Field teams typically make estimates by observing traffic in stores.

* Analyzing credit card data, compiled by companies such as MasterCard