I chose that statistic to be a bit tongue-in-cheek, cf
> While 'ecstasy' is the popular name for MDMA, the functional definition of ecstasy is any pill represented as MDMA on the street. Ecstasy pills are notoriously unreliable in content, more so than most other street drugs, and commonly contain either caffeine, ephedrine, amphetamines, MDA, MDE, DXM, or--in rare cases--DOB, and don't necessarily contain MDMA or any psychoactive.
To follow up on your response and clarify some: in your dataset, not only do 91.7% of the vendors of 'speed and MDMA' also sell 'Ecstasy'; 76.8% of the vendors of 'Stimulants and Ecstasy' also sell 'MDMA'.
If I understand correctly, this means that vendors were significantly more likely to mention 'Ecstasy' in a product name (or description) if they claimed to be selling 'MDMA' than they were to mention 'MDMA' in a product name/description if they claimed to be selling 'Ecstasy', reinforcing the point that you have just made.
> While 'ecstasy' is the popular name for MDMA, the functional definition of ecstasy is any pill represented as MDMA on the street. Ecstasy pills are notoriously unreliable in content, more so than most other street drugs, and commonly contain either caffeine, ephedrine, amphetamines, MDA, MDE, DXM, or--in rare cases--DOB, and don't necessarily contain MDMA or any psychoactive.
https://www.erowid.org/chemicals/mdma/mdma_basics.shtml