The phrase "a frequency of one" is correct and usable in written English.
It can be used in contexts related to statistics, data analysis, or any situation where you are discussing occurrences or repetitions of an event.
Example: "In our study, we found that the rare event had a frequency of one, indicating it occurred only once during the observation period."
Alternatives: "an occurrence of one" or "a count of one".
Certain other medications are used on a daily, long-term basis if migraines have become extremely painful or have reached a frequency of one per week.
Among other findings, researchers found that in mice, fathers contributed mitochondrial DNA to their offspring at a frequency of one in 10,000 and that, contrary to popular belief, the mitochondria in human sperm can enter the egg during fertilization.
Two remobilization events were observed with a frequency of one every 23 generations, a rate far below what would be useful to drive anti-pathogen transgenes into wild mosquito populations.
To commemorate the German pioneer Heinrich Hertz, who carried out some of the early radio experiments, the cycle per second is now called a hertz so that a frequency of one cycle per second is written as one hertz (abbreviated Hz).
In this study, fracture fragments were detected at a frequency of one out of four cases.
At the beginning, the attacks usually occurred during the menstrual period with a frequency of one episode every other month.
Hypospadias is one of the most frequent congenital anomalies in boys, occurring with a frequency of approximately one in every 250 newborn males (1, 2).
By the convention of sleep researchers, our deepest, most oblivious slumber is characterized by EEG patterns known as delta waves very slow, high amplitude waves (about 300 microvolts, at a frequency of about one wave per second).
The exacerbations, in bouts of a few minutes to a few hours, had a frequency of about one to two attacks per week.
Circulating levels of glucocorticoids demonstrate a circadian pattern which consists of a series of pulses of varying amplitude with a frequency of approximately one pulse per hour (1).
Indeed, systematic studies of human karyotypes have revealed that detectable neo-rearrangements occur at a frequency of approximately one in a thousand [ 53].
