The phrase "a marginal level" is correct and usable in written English.
It can be used to describe a level that is minimal or just above a threshold, often in contexts such as performance, quality, or measurement.
Example: "The project achieved a marginal level of success, barely meeting the expectations set by the stakeholders."
Alternatives: "a minimal level" or "a slight level".
However, the returns still continue to be at a marginal level (Scott and Bruce 1987).
Advantages of the short SXD were demonstrated, but the total peak heat load was a marginal level (10 MW m−2) for the engineering design.
Results show that under various loading levels, the stresses and deflections in the VGU of this novel glazing system always remain at a marginal level, and hence the likelihood of breakage for VGUs can be reduced significantly.
Although one of the proposed hypotheses was confirmed and another one reached a marginal level of statistical significance (Crit.Av., p = .055), still we suggest that this variable be analysed in another sample that presents a higher degree of distortion to understand what really is associated with distortion of disgust expressions.
For this reason, it is important to determine whether a marginal level expression can improve life quality and prolong lifespan.
In the full statistical model, the Yellow morph decreased slightly in frequency over time, but only at a marginal level of significance (P = 0.036, Table 2).
Mr. Hollinger's statistic (as its name implies) estimates the number of additional wins that a player is worth to his team, above a marginal-level player that could be picked up for the minimum salary.
This index showed that the Zhoukoudian area of Beijing was a moderate or marginal level selenium ecological landscape.
"It may be that earthquakes are predictable only at a very, very marginal level," he says, which may only become apparent by studying large datasets.
The differences were small in the groups that had an adequate or marginal level of health literacy and only few of the differences reached statistical significance at p<0.05.
By qPCR, AD cases showed reduced PLD3 mRNA levels, when compared with the levels in non-AD cases at a marginal significance level (P =0.0499).
