For example, the dose of black cohosh is usually based on the amount of the compound 27-deoxyactein.
Many herbal products on the market are standardized, but some are not. There are some known problems with the standardization process. In some cases, sometimes the product is standardized to a compound that's later found not to be the active ingredient, or to be one of several. Also, different companies use different markers or different amounts of the same markers.