The disavantages of group intelligence tests include that.
Advantages of group tests:
can be administered to very large numbers simultaneously
simplified examiner role
scoring typically more objective
large, representative samples often used leading to better established norms
Disadvantages of group tests:
examiner has less opportunity to establish rapport, obtain cooperation, and maintain interest
not readily detected if examinee tired, anxious, unwell
evidence that emotionally disturbed children do better on individual than group tests
examinee�s responses more restricted
normally an individual is tested on all items in a group test and may become boredom over easy items and frustrated or anxious over difficult items
individual tests typically provide for the examiner to choose items based on the test takers prior responses - moving onto quite difficult items or back to easier items. So individual tests offer more flexibility.