The phrase "a valid day" is correct and usable in written English.
It can be used in contexts where you are discussing the legitimacy or acceptability of a specific day, often in relation to scheduling or events.
Example: "Please confirm if next Monday is a valid day for our meeting."
Alternatives: "an acceptable day" or "a legitimate day".
Specifically, each monitor had to have at least 77 valid days, with a valid day defined as having at least nine hourly observations between 0800 and 1950 hr.
For the purposes of this study at least 3 valid days of data were required; a valid day constituted at least 12 h of wear time.
At least three valid days of data were required; a valid day constituted at least 10 h of wear time as assessed by the pedometer log.
Parents and children were included in the primary analyses if they provided at least three days of valid data where a valid day was defined as the provision of at least 500 minutes of data [ 20].
In addition we repeated all analyses with the outcome being wearing the accelerometer for the full-requested 5 days, again with ≥8 h/day taken as a valid day of wear-time (referred to as 'requested' wear-time).
At least five valid days (including one weekend day) were required for inclusion in the analysis; a valid day was defined as a 24-hour period in which more than 600 minutes of wear time were recorded [ 31, 32].
33 Three urine samples contained glucocorticoids above the MRPL; after consultation with the FIFA Medical Board, a valid TUE was effective for all of them and the results were reported as negative.
The mean number of valid days (for those with at least 1 valid day) was 6 days.
In this study, we defined a valid GPS day as a 16-hr day (7:00 AM to 10 59 PM) with no more than 50% of expected GPS data that was missing, equivalent to ≥8 hours of GPS data during typical waking hours.
Previous studies of GPS activity tracking have used various criteria for a valid GPS day.
a Valid GPS day: ≥50% of GPS data between 7 00 AM and 10 59 PM.
