The phrase "a significant effect once" is grammatically correct but may lack clarity without context.
It can be used when discussing the impact of an event or action that occurred at a specific time in the past.
Example: "The new policy had a significant effect once it was implemented, leading to improved employee satisfaction."
Alternatives: "a notable impact at one time" or "a considerable influence previously".
The education track system has such a significant effect that once a student steps on the track of vocational education, it is very hard for them to go back to the academic track.
However, that study did not find a significant effect of once-daily vs twice-daily regimens on virological outcome, possibly because of insufficient statistical power [ 13].
A Chicago study, which used a composite measure of pre-morbid reading ability, also failed to find a significant effect of this once other variables, including race, were adjusted for [ 30].
Furthermore, in several studies, only few variables were found to have a significant effect on mathematics achievement once the socioeconomic level of schools and students was taken into account (Wiberg et al. 2013; Wiberg and Rolfsman 2013).
A simulation study on shale gas production in a 0.0001-mD shale matrix shows that the percentage of area filled by proppant and the proppant concentration in the network does not have a significant effect on gas production once the un-propped fracture network conductivity reaches 5 mD ft (Cipolla et al. 2009).
Although co-morbidity had a significant effect in the univariable analyses, once other health measures were adjusted for, the effect of co-morbidity lost significance.
These results sharply contrast with the population structure described in this study, where a significant effect of isolation-by-distance (once outliers have been excluded) and at least short-term temporal stability of population structure was observed.
Relationship status was found to be an independent predictor of HSV-2 seroprevalence among adults age 30 to 49, even when lifetime number of partners was taken into account, though relationship status no longer had a significant effect at ages 20 to 29 once partner number was included in the model.
Our results once again suggest a significant effect of restricted standard of living, supporting Hypothesis 1.
