Yes there have been studies performed comparing efficacy across the different routes of administration. However, there are several variables that make it hard to determine efficacy including:
- Variation among cannabis products
- Cannabis drug interactions
- Difference in cannabis metabolism among individuals
- Uniform dosing
- Limited human cannabis studies
Here is an article below that discusses differences among smoking, oral, oromucosal, rectal, and topical ingestion of cannabis.
Human Cannabinoid Pharmacokinetics