The phrase "ascertained by many" is correct and usable in written English.
It can be used when referring to information or knowledge that has been confirmed or established by a large number of people or sources.
Example: "The effectiveness of the new policy has been ascertained by many experts in the field."
Alternatives: "determined by numerous" or "verified by many".
Educational attainment was ascertained by asking, "How many years of formal education have you had?" with possible answers of "less than 6 years," "6 9 years," "10 12 years," "more than 13 years," and "other".
In Chandler's case, the measure of his worthiness is probably best ascertained by answering the question many New York fans have asked themselves all season: Where would the Knicks be without him?
The reproducibility and statistical significance of these observations was ascertained by repeating this experiment many times, which also allowed us to conclude that MeCP2 overexpression results in a similar 40% decrease of all three MHC class I molecules and of β-2-microglobulin (Figure 1B).
This was ascertained by the question: "How many times have you been treated for any psychological or emotional problems in outpatient counseling in the past year?" Responses were dichotomized as 1 for attending at least one outpatient mental health counseling appointment and 0 for not attending any mental health counseling appointments.
Previously had sex was coded as "yes" or "no", based on the answer to the question: "Have you ever had sexual intercourse?" Number of lifetime sexual partners was ascertained by the response to "How many sexual partners have you had altogether?" The variable was dichotomized so that ≥ 3 was coded as "high" and < 3 as "low".
Maternal weight was measured or ascertained by trained nurses, which is a strength compared with many previous studies as weight usually is completely self-reported [ 9, 13, 15].
3) Experience of being drunk was ascertained by the response to 'During the past 12 months, how many times did you get drunk (feeling light-headed, headache, sleepy, etc).
Maternal average nightly sleep duration during pregnancy was ascertained by asking women the following question: "Since becoming pregnant, how many hours per night do you sleep?" A similar question was asked for sleep duration before pregnancy.
Maternal average nightly sleep duration during early pregnancy was ascertained by asking women the following question: "Since becoming pregnant, how many hours per night do you sleep?" Responses were reported as integers.
Quit attempts by smokers were ascertained by asking whether they had tried to quit smoking in the last 12 months and if so how many times they had done so.
