There are several important metrics that e-commerce companies should track to evaluate their performance and make informed business decisions. These metrics help measure various aspects of an e-commerce business, including sales, customer behavior, marketing effectiveness, and operational efficiency. Here are some of the most crucial metrics for e-commerce companies:

1. Conversion Rate: This metric measures the percentage of website visitors who complete a desired action, such as making a purchase. A high conversion rate indicates effective marketing and a user-friendly website. Calculated as: (Number of Conversions / Number of Website Visitors) * 100. 

2. Average Order Value (AOV): AOV measures the average amount spent by customers on each transaction. It helps determine the effectiveness of upselling and cross-selling strategies. A higher AOV indicates increased revenue per customer. Calculated as: Total Revenue / Number of Orders.

3. Customer Acquisition Cost (CAC): CAC measures the cost incurred to acquire a new customer. It includes marketing expenses, advertising costs, and other related expenses. It is essential to keep CAC lower than the average customer's lifetime value (LTV) to ensure profitability. Calculated as: Total Marketing and Sales Expenses / Number of New Customers Acquired.

4. Customer Lifetime Value (LTV): LTV represents the total revenue generated from a customer throughout their relationship with the company. It helps determine the long-term value of acquiring and retaining customers. A higher LTV indicates higher customer loyalty and profitability. Calculated as: Average Purchase Value * Purchase Frequency * Customer Lifespan.

5. Cart Abandonment Rate: This metric measures the percentage of customers who add items to their cart but do not complete the purchase. A high abandonment rate may indicate issues with the checkout process, pricing, or shipping costs. Calculated as: (Number of Carts Abandoned / Number of Carts Created) * 100.

6. Return on Advertising Spend (ROAS): ROAS measures the revenue generated from advertising campaigns compared to the cost of those campaigns. It helps assess the effectiveness of marketing efforts and optimize advertising budgets. Calculated as: (Revenue from Ad Campaign / Cost of Ad Campaign) * 100.

7. Customer Retention Rate: This metric measures the percentage of customers who continue to make purchases from the e-commerce company over a specific period. A high retention rate indicates customer satisfaction and loyalty. Calculated as: ((Number of Customers at End of Period - Number of New Customers) / Number of Customers at Start of Period) * 100.

8. Inventory Turnover: Inventory turnover measures how quickly a company sells its inventory within a given period. It helps assess inventory management efficiency and avoid overstocking or stockouts. Calculated as: Cost of Goods Sold / Average Inventory Value.

These are just a few of the many metrics that e-commerce companies should track. The choice of metrics may vary depending on the company's goals, industry, and business model. Regular monitoring and analysis of these metrics enable companies to identify areas for improvement, optimize marketing strategies, and drive overall business growth.

References:
- Shopify: Ecommerce Metrics: 14 Essential Reports for Tracking Your Online Store's Growth - https://www.shopify.com/blog/ecommerce-metrics
- Kissmetrics: 9 Ecommerce Metrics & KPIs to Measure Your Online Store's Success - https://www.kissmetrics.io/ecommerce-metrics/