The phrase "are mostly a function of" is correct and usable in written English.
It can be used to indicate that something is primarily determined or influenced by certain factors or variables.
Example: "The results of the experiment are mostly a function of the temperature and pressure conditions."
Alternatives: "are primarily determined by" or "are largely influenced by".
That said, the way you phrase the question — how can HE (i.e., Obama) improve joblessness, etc., is a symptom of our tendency to assume that political outcomes are mostly a function of Presidential activity.
If goods and services prices are mostly determined by slack across the euro-area economy as a whole while wages are mostly a function of national labour-market tightness, then fiscal stimulus in Germany would raise German wages more than it would raise German inflation (or euro-area inflation).
Rydex's higher costs are mostly a function of trading costs related to quarterly rebalancing.
Current design codes propose values for the effective width which are mostly a function of the beam span ignoring in this way the influence of other important parameters.
The testing methodology is that we would first run the KAQ algorithm approacomplexitypecific, anumbers use the sare number of comparableRANDOM.
This result is to be expected since these parameters are mostly a function of the slurry concentration from which the corresponding matrices were produced, and in all cases identical 1% (w/v) suspensions were employed to obtain the scaffolds.
That's mostly a function of instrumentation, which tends here toward the mellower end of the spectrum.
How they feel about the economy seems to be mostly a function of gasoline prices, interest rates and, especially, unemployment.
Duhon's marked improvement in assists a game (8.5 from 4.0) has been mostly a function of increased playing time, nearly 40 minutes a game.
First Amendment doctrine was mostly a function of ad hoc decision-making as the Court grappled with the issues posed by Communist Party advocacy and association.
What we discovered is that the marriage, so to speak, between Mr. Booker and the party of George W. Bush is mostly a function of where he is running and what he could face as mayor.
