The phrase "a certain mastery of" is correct and usable in written English.
It can be used to describe a level of skill or proficiency in a particular area or subject.
Example: "To succeed in this field, one must demonstrate a certain mastery of the relevant techniques and theories."
Alternatives: "a degree of expertise in" or "a level of proficiency with".
The tobacco bill, for example, is needed because "3,000 kids will start smoking every day, and 1,000 of them will die from smoking-related illness".. And, for all the tilting at windmills, he has a certain mastery of the political process: campaign-finance reform, for example, was sustained as an issue long beyond the patience of Mr Lott and the House Speaker, Newt Gingrich.
If Davis is to have a chance to beat Abbott, a certain mastery of Texas media will be required, and instead there has been an exhibition of failure.
Risk agility implies a certain mastery of risk, decision making under opacity, and a level of simplicity in the face of complex, heavily interconnected systems.
He had a certain mastery and he gave occasional intimations of power in reserve, but his poems bored me stiff.
"Some kids leave elite prep schools like St . Pauls or Choate with entry into certain colleges, mastery of certain protocols," she writes.
Like skiing, it requires a certain degree of mastery, a countervailing ability to contend with the panic and reassert a measure of stability.
Some games level that a little with dynamic difficulty, but basically, the entire structure is, 'here's a skill, practice it and we'll only let you progress once you've demonstrated a certain level of mastery'.
Nevertheless, the main application of the Rasch analysis techniques has been to create banks of items of known difficulty from which tests can be constructed such that candidates of a certain standard of mastery consistently achieve a passing score while others below that level consistently do not (Alderson et al. [1995]).
Such tests may be deemed to be unreliable not only due to lack of homogeneity, but as a result of inconsistency in distinguishing candidates who have attained a certain level of mastery from those who have not (Bachman and Palmer [1996]).
