Which method is best to test assumptions about increased sales through better customer service?

The best method to test assumptions about increased sales through better customer service is percent change. This approach allows for a straightforward calculation of the difference in sales before and after improvements in customer service. By expressing this difference as a percentage of the original sales, you can easily assess the impact of the changes made. This quantifiable measure gives clear insights into how much sales have truly increased and emphasizes the effectiveness of customer service initiatives.

While customer feedback is valuable for understanding customer satisfaction and potential service improvements, it does not provide a direct measure of sales changes. Historical analysis can help identify past trends in sales and customer service but may not accurately reflect current conditions or the specific impact of recent changes. Similarly, sales forecasts are projections based on various assumptions and can be influenced by many extraneous factors, making them less effective for directly measuring the impact of improved customer service on actual sales figures. Percent change, on the other hand, focuses directly on the outcome of interest—sales—in relation to the service changes implemented.