Despite their advantages, sealed envelopes have some limitations:
1. Tampering Risk: There is a potential risk that the envelopes could be tampered with, compromising the study’s integrity. 2. Human Error: Mistakes in the preparation or handling of the envelopes could lead to allocation errors. 3. Lack of Flexibility: Once the envelopes are prepared, it is difficult to make any adjustments without compromising the randomization process.
