The phrase "a constant correlation between" is correct and usable in written English.
It can be used when discussing a consistent relationship or connection between two or more variables or factors.
Example: "The study found a constant correlation between exercise frequency and overall health."
Alternatives: "a consistent relationship between" or "a steady link between".
One might notice a constant correlation between the date of the first frost and fluctuations in the price of wheat.
Besides a constant correlation between EC TDS, EC TH and EC Cl in both the seasons, K and F did not show any correlation with any parameters during both the seasons.
The covariance structure that assumes a constant correlation between any two measurements on a single subject yielded a better model fit (lower AIC value) and was applied in all mixed-effects models.
No inter-marker-correlation was observed for the other factors except for a constant correlation between VEGF-165 and TIMP-1 before surgery (r = 0.467; p = 0.008), after surgery (r = 0.522; p = 0.002), during chemotherapy (r = 0.437; p = 0.009) and after chemotherapy (r = 0.408; p = 0.017).
We chose the most appropriate covariance structure by comparing Akaike information criterion (AIC) values between a covariance that assumes a constant correlation between any pair of measurements made on the same subject versus a first-order autoregressive structure, which assumes that measurements on the same subject taken closer in time are more highly correlated than those taken further apart.
Ahn et al. ([2008]), Cho et al. ([2013]) and Kindaichi et al. ([2006]) used qPCR to determine maximum biomass specific growth rates in nitrifying communities based on the abundance of DNA copy numbers, and assuming a constant correlation factor between DNA content and biomass.
The first part, β1, g, in equation 1 is the variance bias and accounts for a constant correlation that exists between any two input points.
We analyzed data using the SAS statistical package and mixed models (PROC MIXED) (SAS Institute Inc., Cary, NC, USA) taking into account repeated observations and assuming constant correlation between observations within a subject.
An exchangeable correlation structure, with constant correlation between repeated measures of the outcome within each subject over time, was chosen based on AIC, from among biologically plausible candidates.
To account for the non-independence of pregnancies contributed by the same woman, we used generalized estimating equations (GEE) [ 22, 23], for which we assumed constant correlation between pregnancies contributed by the same mother.
At all stations a constant significant correlation between temperature and presumptive Vibrio parahaemolyticus was reported suggesting that this abiotic factor exerted a major control on this bacterial group and its distribution in the water column is not related to the biodeposition of the mussel farm.
