The phrase "are much less robust" is correct and usable in written English.
It can be used to compare the strength or durability of two or more subjects, indicating that one is significantly weaker than the other.
Example: "The new software solutions are much less robust than the previous versions, leading to frequent crashes."
Alternatives: "are significantly weaker" or "are far less durable."
The frozen embryos at fertility centers are much less robust, medical experts say.
However, in contrast to DNA-based markers, metabolites are much less robust since they are responsive to the environment, and might be tissue-specific and developmentally regulated.
It turned out, however, that the phase angles of the descriptors are much less robust with respect to small changes in the contour coordinates.
The very low incidence of cases in Group Ib (low pEGFR-IR, high CB1IR) means that the survival curves for this group are much less robust than for the other groups.
The other limitation of the ecological approach based on nonparametric correlations is its inability to take multiple factors into account through a multiple regression or partial correlation analysis, as the association between factors is not known and nonparametric approaches to partial correlation are much less robust than their parametric counterparts.
"The economy was much less robust and diversified, so there really wasn't anything else to do".
The language is much less robust than that advocated by Tim Loughton, the sacked children's minister, who demanded strong wording in favour of shared parenting after divorce.
"Momentum is much less robust now than it was then, and therefore we are much more vulnerable to fiscal shocks now".
One positive thing in Bernanke's speech — I'm trying to look on the bright side — is that for what seems to me the first time he has more or less acknowledged that we are not, in any real sense, experiencing a recovery: Notwithstanding these more positive developments, however, it is clear that the recovery from the crisis has been much less robust than we had hoped.
The phase normalisation obviously is much less robust.
The rationale for targeted early interventions then is much less robust than it might appear.
