"hamper the effectiveness" is correct and usable in written English.
You can use it when referring to something that hinders the success or efficiency of something else. For example, "Unfavourable weather conditions have been known to hamper the effectiveness of crop yields."
These overlapping responsibilities are a conflict of interest for CNOOC and hamper the effectiveness of the joint venture".
The criticism from the Southern Poverty Law Center seemed to do little to hamper the effectiveness of CIS and the other groups Tanton helped form.
Poor delivery efficiency continues to hamper the effectiveness of cancer therapeutics engineered to destroy solid tumors using different strategies such as nanocarriers, targeting agents, and matching treatments to specific genetic mutations.
Perhaps teacher scores will fluctuate within a certain range in the short term but stay within that range over the long term, but, for many educational reform policy programs, teachers would be evaluated on a year-to-year basis, and this kind of swing in scores could hamper the effectiveness of such evaluation.
Still the acid could hamper the effectiveness of incorporated drugs or proteins.
20, 21 However, rising insecticide resistance of vectors could hamper the effectiveness of such insecticide-based interventions.
Until now, low-level expression, position effects, and transcriptional silencing have hampered the effectiveness of retroviral-mediated gene transfer.
Although wartime conditions hampered the effectiveness of his administration, he introduced programs that set important precedents for subsequent governments.
Although gasoline sulfur does not pose a public-health threat on its own, it hampers the effectiveness of catalytic converters, which in turn leads to greater tailpipe emissions.
