The phrase "a certain month or" is correct and usable in written English.
It can be used when referring to an unspecified month in a context where the exact month is not important or is to be determined later.
Example: "We will schedule the meeting for a certain month or when everyone is available."
Alternatives: "an unspecified month" or "a particular month".
Similar effects were observed for third-generation cephalosporin and fluoroquinolone use, i.e., an increase of 10 DDD per 1,000 patient-days on a certain month or 30 more treated patients, resulted in an increase in %MRSA by 4.99 after 12 months for third-generation cephalosporins and by 4.40 after 11 months for fluoroquinolones.
For example, an increase in macrolide use by 10 DDD per 1,000 patient-days on a certain month, or 30 more patients treated with a macrolide as compared with the previous month, would lead to a direct increase in %MRSA by 0.83, 1 month later, by 0.55, 2 months later and by 0.27, 3 months later.
Alternatively, if a hotel sees an unreasonably low margin on its online revenue in a certain month, measures like cost of acquisition or upsell rate will likely explain why.
What you spend might vary wildly, depending on whether you drink at home or at a bar or restaurant, whether your social calendar is packed in a certain month, whether a special occasion ratchets up your purchases.
One reason that the statistics have not reflected the full impact from Asia is that the Government, when calculating a certain month's import prices, uses the previous month's foreign-exchange figures.
It can happen that most of the data in a certain month are obtained when the satellite is under a high-temperature condition, and monthly averaging cannot work for minimizing the temperature effect.
If company history is any indication, Apple tends to designate a certain month that it releases a product and then sticks to it.
For example, a patient who is registered as inpatient in a certain month may be registered as outpatient in the next month, but never at the same month.
The release of each sterilised female resulted in one of three types of event: released in a certain month and not caught a second time; first released in a certain month and caught a second time, after a certain interval, for euthanasia; and first released in a certain month and caught a second time after a certain interval because the ear notch was missed but not caught again.
