The phrase "a critical variable in" is correct and usable in written English.
It can be used when discussing an important factor or element that influences a particular situation or outcome.
Example: "In the success of the project, time management is a critical variable in ensuring that deadlines are met."
Alternatives: "an essential factor in" or "a key element in".
He remains at the top of the governing People's Democratic Party, an immense patronage machine — a critical variable in Nigeria's political system.
These results show that the choice of anesthetic protocol is a critical variable in designing behavioral neuroscience experiments using neurosurgical procedures.
The Russia-China axis of obstruction at the Security Council has now become a critical variable in the council's decision-making process.
The price of corn is a critical variable in the world food equation, and food markets are on edge because American corn supplies are plummeting.
This highlights that the background diet is a critical variable in the risk assessment of POPs and warrants further investigation of dietary mediated toxicity of food contaminants.
Even for the elite elements of society, the environment was a critical variable in how palace walls were decorated, how gardens and parks were created, and how tribute was collected.
Temperature is a critical variable to be optimized in any enzymatic process, producing opposite effects on enzyme activity and inactivation rate.
Adding thermal dynamics to the SPM serves a two-fold purpose: improving the accuracy of SoC estimation and keeping track of the average temperature which is a critical variable for safety management in lithium-ion batteries.
This is very different from what many call "sensitivity analysis". It's about creating a coherent set of scenarios across all critical variables in an analytically rigorous fashion.
James Payne suggests another possibility: that the critical variable in the indulgence of violence is an overarching sense that life is cheap.
Or, to put it another way, we are the critical variable in this equation.
