The phrase "a curvilinear relation between" is correct and usable in written English.
It can be used in contexts involving mathematics, statistics, or scientific discussions where the relationship between two variables is not linear.
Example: "The study revealed a curvilinear relation between temperature and the rate of photosynthesis in plants."
Alternatives: "a non-linear relationship between" or "a curved relationship between".
There is a curvilinear relation between risk and the DPTRS.
We found a curvilinear relation between predictors of mortality and vaccination.
Counterintuitively, whereas the diurnal rhythm of cortisol is consistent across development, there appears to be a curvilinear relation between age and cortisol reactivity.
We used linear regression to model mean BMI according to age, cohort, SES and smoking status, allowing for a quadratic term for age to account for a curvilinear relation between BMI and age and interactions between SES and age and between SES and cohorts to test whether the relation between SES and BMI changed across subsequent cohorts.
We find no support of any curvilinear relation between diversity and innovation.
A second study reported a significant curvilinear relation between amniotic fluid testosterone and eye contact in boys but not in girls [ 65], but this curvilinear relationship, as opposed to a linear relationship, had not been predicted.
In another recent autopsy study, there was a significant curvilinear relation between β-cell volume and fasting blood glucose level, and β-cell deficiency was associated with a steep increase in blood glucose with further decrement in β-cell mass (26).
Decline in hunting ability due to physiological deterioration at old age was found in wolves [49] and aboriginal human hunters [50], also supporting a curvilinear relation with age.
Similarly, vaccine coverage bore a curvilinear relation with the insurance risk score.
However, the change in end-expiratory Ppl and EELV had a curvilinear relation, indicating that EELV changes were dependent on the degree of expiratory rib cage activity.
We performed three sensitivity tests related to the modeling of the difference in unhealthful and healthful food densities as a curvilinear relation.
