Running online controlled experiments--also known as A/B tests--can be difficult. A simple test can be used to detect a wide variety of data quality issues. Only sample counts are required as input, so this test can be used even when experimenters only have access to summary statistics; such as when using third-party tools, or reading academic research reports.
Everyone running A/B tests should be doing this important SRM test. This simple website can be used to do so.