The MENSA qualifying test is not technically an IQ test, and yes, it is different from a gold-standard individually-administered Wechsler or Stanford-Binet. Mensa's target population is the top 2%. Davidson's target population is the top 0.1%. Anyone who has documentation of cognitive ability that is DYS-eligible also has documentation that supports Mensa.

...pronounced like the long vowel and first letter of the alphabet...