The phrase "a critical proportion" is correct and usable in written English.
It can be used when discussing a significant or essential amount or ratio of something in a particular context, often in scientific, statistical, or analytical discussions.
Example: "In order to achieve the desired outcome, we need to ensure that a critical proportion of the participants are engaged in the study."
Alternatives: "an essential ratio" or "a significant amount".
Mass vaccination allows us to study how immunity operates at the group level; denser populations are more prone to transmitting disease between individuals, but once a critical proportion of the population becomes immune, "herd immunity" emerges.
The idea is that when a critical proportion of a group is immune to a disease, too few individuals are susceptible for that disease to be passed from one to another.
To put it more bluntly, in 2014, thriving newsrooms will share the following characteristics: (a) they will be fastest to inject a critical proportion of new blood in their ranks and (b) they will invest in training to add the skills, mostly tech ones, required by modern journalism.
Simulation results validate a critical proportion of committed individuals as a plausible basis for ideological shifts in societies.
A critical proportion of committed minority ensures the conversion of a certain fraction of moderates to their extremist counterpart, thereby leading to a consensus towards the minority ideology.
Increasing their number in SSA to cover a critical proportion of the population, especially urban populations, must be carefully planned.
Biochemical defects and tissue dysfunction will not be apparent until the mutated mtDNAs reach a minimum critical proportion, and this threshold level varies among different tissues.
One can argue that unless a minimum critical proportion of consumers (sellers) invest in cashless instruments, sellers (consumers) will not invest as well.
Below a proportion (critical proportion = 1 %), the strain was classified as sensitive; otherwise classified as resistant.
Spilling blood represents a more concrete injury than does streaming tears but both represent an injury, sometimes of critical proportion.
These models rely on computing the Pc, which is extensively used as an estimate of the critical proportion of the population- or cohort-based vaccination coverage required to limit an epidemic.
